Image capturing lens system, image capturing unit and electronic device including eight lenses of +−+−++−+, +−+−+−+ or +−−+−−+− refractive powers

ABSTRACT

An image capturing lens system includes four lens groups which include eight lens elements. The four lens groups are, in order from an object side to an image side: first, second, third and fourth lens groups. The eight lens elements are, in order from the object side to the image side: first, second, third, fourth, fifth, sixth, seventh and eighth lens elements. The first and second lens elements respectively have positive and negative refractive power. At least one lens element in the second through fourth lens groups has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application 63/059,800, filed on Jul. 31, 2020, which is incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates to an image capturing lens system, an image capturing unit and an electronic device, more particularly to an image capturing lens system and an image capturing unit applicable to an electronic device.

Description of Related Art

With the development of semiconductor manufacturing technology, the performance of image sensors has improved, and the pixel size thereof has been scaled down. Therefore, featuring high image quality becomes one of the indispensable features of an optical system nowadays.

Furthermore, due to the rapid changes in technology, electronic devices equipped with optical systems are trending towards multi-functionality for various applications, and therefore the functionality requirements for the optical systems have been increasing. However, it is difficult for a conventional optical system to obtain a balance among the requirements such as high image quality, low sensitivity, a proper aperture size, miniaturization and a desirable field of view.

SUMMARY

According to one aspect of the present disclosure, an image capturing lens system includes four lens groups, and the four lens groups include eight lens elements. The four lens groups are, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. The eight lens elements are, in order from the object side to the image side along the optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element. Each of the eight lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side.

The first lens group includes the first lens element and the second lens element, the second lens group includes the third lens element, the fourth lens element and the fifth lens element, the third lens group includes the sixth lens element and the seventh lens element, and the fourth lens group includes the eighth lens element. The first lens element has positive refractive power. The second lens element has negative refractive power. At least one lens element in the second lens group, the third lens group and the fourth lens group has at least one inflection point in an off-axis region thereof.

A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process, and the third lens group is moved relative to the first lens group along the optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

When an Abbe number of one of the eight lens elements is Vi, a refractive index of the one of the eight lens elements is Ni, a minimum value of Vi/Ni is (Vi/Ni) min, half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the long-focal-length end is TDL, and an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the short-focal-length end is TDS, the following conditions are satisfied: 7.5<(Vi/Ni)min<12.3; 3.0 degrees<HFOVS<25.0 degrees; 0.50<Y11L/Y82L<2.0; 0.50<Y11S/Y82S<2.0; and |TDL/TDS−1|<1.0E−2.

According to another aspect of the present disclosure, an image capturing lens system includes four lens groups, and the four lens groups include eight lens elements. The four lens groups are, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. The eight lens elements are, in order from the object side to the image side along the optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element. Each of the eight lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side.

The second lens group includes at least three lens elements. The first lens element has positive refractive power. The second lens element has negative refractive power. The third lens element has positive refractive power. At least one lens element in the second lens group, the third lens group and the fourth lens group has at least one inflection point in an off-axis region thereof.

A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

When an Abbe number of one of the eight lens elements is Vi, a refractive index of the one of the eight lens elements is Ni, a minimum value of Vi/Ni is (Vi/Ni) min, half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, the following conditions are satisfied: 7.5<(Vi/Ni)min<12.3; 3.0 degrees<HFOVS<25.0 degrees; 0.50<Y11L/Y82L<2.0; and 0.50<Y11S/Y82S<2.0.

According to another aspect of the present disclosure, an image capturing lens system includes four lens groups, and the four lens groups include eight lens elements. The four lens groups are, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. The eight lens elements are, in order from the object side to the image side along the optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element. Each of the eight lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side.

The first lens element has positive refractive power. The second lens element has negative refractive power. The third lens element has positive refractive power. The eighth lens element has positive refractive power. At least one lens element in the first lens group, the second lens group, the third lens group and the fourth lens group is made of plastic material. At least one lens element in the second lens group, the third lens group and the fourth lens group has at least one inflection point in an off-axis region thereof.

A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

When an Abbe number of one of the eight lens elements is Vi, a refractive index of the one of the eight lens elements is Ni, a minimum value of Vi/Ni is (Vi/Ni) min, half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, the following conditions are satisfied: 7.5<(Vi/Ni)min<12.3; 3.0 degrees<HFOVS<25.0 degrees; 0.50<Y11L/Y82L<2.0; and 0.50<Y11S/Y82S<2.0.

According to another aspect of the present disclosure, an image capturing unit includes one of the aforementioned image capturing lens systems and an image sensor, wherein the image sensor is disposed on an image surface of the image capturing lens system.

According to another aspect of the present disclosure, an electronic device includes at least two image capturing units located on the same side of the electronic device. The at least two image capturing units includes a first image capturing unit and a second image capturing unit. The first image capturing unit includes one of the aforementioned image capturing lens systems and an image sensor disposed on an image surface of the image capturing lens system. The second image capturing unit includes an optical lens assembly and an image sensor disposed on an image surface of the optical lens assembly. In addition, half of a maximum field of view of the second image capturing unit ranges from 30 degrees to 60 degrees.

According to another aspect of the present disclosure, an electronic device includes at least two image capturing units located on the same side of the electronic device. The at least two image capturing units includes a first image capturing unit and a second image capturing unit. The first image capturing unit includes one of the aforementioned image capturing lens systems and an image sensor disposed on an image surface of the image capturing lens system. The second image capturing unit includes an optical lens assembly and an image sensor disposed on an image surface of the optical lens assembly. In addition, half of a maximum field of view of the second image capturing unit ranges from 30 degrees to 60 degrees, and a movement direction of lens groups of the first image capturing unit is perpendicular to an optical axis of at least another of the at least two image capturing units.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood by reading the following detailed description of the embodiments, with reference made to the accompanying drawings as follows:

FIG. 1 is a schematic view of an image capturing unit at the short-focal-length end according to the 1st embodiment of the present disclosure;

FIG. 2 is a schematic view of the image capturing unit at the long-focal-length end according to the 1st embodiment of the present disclosure;

FIG. 3 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 1st embodiment;

FIG. 4 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 1st embodiment;

FIG. 5 is a schematic view of an image capturing unit at the short-focal-length end according to the 2nd embodiment of the present disclosure;

FIG. 6 is a schematic view of the image capturing unit at the long-focal-length end according to the 2nd embodiment of the present disclosure;

FIG. 7 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 2nd embodiment;

FIG. 8 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 2nd embodiment;

FIG. 9 is a schematic view of an image capturing unit at the short-focal-length end according to the 3rd embodiment of the present disclosure;

FIG. 10 is a schematic view of the image capturing unit at the long-focal-length end according to the 3rd embodiment of the present disclosure;

FIG. 11 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 3rd embodiment;

FIG. 12 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 3rd embodiment;

FIG. 13 is a schematic view of an image capturing unit at the short-focal-length end according to the 4th embodiment of the present disclosure;

FIG. 14 is a schematic view of the image capturing unit at the long-focal-length end according to the 4th embodiment of the present disclosure;

FIG. 15 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 4th embodiment;

FIG. 16 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 4th embodiment;

FIG. 17 is a schematic view of an image capturing unit at the short-focal-length end according to the 5th embodiment of the present disclosure;

FIG. 18 is a schematic view of the image capturing unit at the long-focal-length end according to the 5th embodiment of the present disclosure;

FIG. 19 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 5th embodiment;

FIG. 20 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 5th embodiment;

FIG. 21 is one perspective view of an electronic device according to the 6th embodiment of the present disclosure;

FIG. 22 is another perspective view of the electronic device in FIG. 21 ;

FIG. 23 is a cross-sectional view of two image capturing units of the electronic device in FIG. 21 ;

FIG. 24 is a perspective view of an electronic device according to the 7th embodiment of the present disclosure;

FIG. 25 shows a schematic view of Y11S, TDS, BLS, ImgHS, Y82S, and inflection points and a critical point of the eighth lens element according to the 1st embodiment of the present disclosure;

FIG. 26 shows a schematic view of Y11L, TDL, BLL, ImgHL, Y82L, TG1, TG2, TG3 and TG4 according to the 1st embodiment of the present disclosure;

FIG. 27 shows a schematic view of a configuration of a light-folding element in an image capturing lens system according to one embodiment of the present disclosure;

FIG. 28 shows a schematic view of another configuration of a light-folding element in an image capturing lens system according to one embodiment of the present disclosure; and

FIG. 29 shows a schematic view of a configuration of two light-folding elements in an image capturing lens system according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

An image capturing lens system includes four lens groups, and the four lens groups include eight lens elements. The four lens groups are, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. The eight lens elements are, in order from the object side to the image side along the optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element. Each of the eight lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. For example, in one configuration, the first lens group includes the first lens element and the second lens element, the second lens group includes the third lens element, the fourth lens element and the fifth lens element, the third lens group includes the sixth lens element and the seventh lens element, and the fourth lens group includes the eighth lens element.

According to the present disclosure, the focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process, and the image capturing lens system has a long-focal-length end and a short-focal-length end. Therefore, the configuration of four lens groups and eight lens elements is favorable for increasing the zoom ratio and improving image quality. Please refer to FIG. 1 and FIG. 2 , which are schematic views of an image capturing unit respectively at the short-focal-length end and the long-focal-length end according to the 1st embodiment of the present disclosure. Moreover, there is no relative motion between lens elements of one lens group in the zooming process (e.g., there is no relative motion between the lens elements of the first lens group). Therefore, it is favorable for simplifying the structure of the image capturing lens system.

The first lens group includes at least one lens element. Moreover, in one configuration where the first lens group includes two lens elements, it is favorable for reducing the outer diameter at the object side of the image capturing lens system and obtaining a telephoto configuration in the image capturing lens system. Moreover, the first lens group can have negative refractive power. Therefore, it is favorable for increasing the zoom ratio.

The second lens group includes at least one lens element. Moreover, second lens group can include at least three lens elements. Therefore, it is favorable for providing consistent image quality in the zooming process. Moreover, in one configuration where the second lens group includes three lens elements, it is favorable for balancing among the zoom ratio, system size and image quality. Moreover, the second lens group is moved relative to the first lens group along an optical axis in the zooming process. Therefore, it is favorable for minimizing mechanical design restrictions of the image capturing lens system. Moreover, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group can be moved along the optical axis toward the object side relative to the first lens group. Therefore, it is favorable for increasing the zoom ratio. In addition, when the image capturing lens system is zooming from the long-focal-length end to the short-focal-length end, the second lens group can be moved along the optical axis toward the image side relative to the first lens group. Moreover, the second lens group can have positive refractive power. Therefore, it is favorable for increasing the zoom ratio and reducing the outer diameter of the image capturing lens system.

The third lens group includes at least one lens element. Moreover, in one configuration where the third lens group includes two lens elements, it is favorable for providing consistent image quality during the zooming process. Moreover, the third lens group can be moved relative to the first lens group along the optical axis in the zooming process. Therefore, it is favorable for correcting aberrations generated during the zooming process and reducing the variation of back focal length. Moreover, the image capturing lens system can focus on an object in a focusing process as an object distance varies, and the third lens group can be moved relative to the first lens group along the optical axis in the focusing process. Therefore, it is favorable for reducing the movement of lens groups in the focusing process. Moreover, when the object distance decreases in the focusing process, the third lens group can be moved along the optical axis toward the image side relative to the first lens group. Therefore, it is favorable for correcting aberrations, such as field curvature, generated during the focusing process. Moreover, third lens group can have negative refractive power. Therefore, it is favorable for correcting aberrations generated during the zooming process.

The fourth lens group includes at least one lens element. Moreover, the fourth lens group can have positive refractive power. Therefore, it is favorable for adjusting the light path and the back focal length in the zooming process.

The refractive power of the first lens group and the refractive power of the second lens group can have opposite signs from each other, or the refractive power of the third lens group and the refractive power of the fourth lens group can have opposite signs from each other. Therefore, it is favorable for correcting aberrations generated during the zooming process. When the refractive power of one lens group and the refractive power of another lens group have opposite signs from each other, it means that one of the lens group has positive refractive power and the other has negative refractive power.

According to the present disclosure, the image capturing lens system further includes an aperture stop, and the aperture stop can be disposed in the second lens group. Therefore, it is favorable for adjusting the relative position of the aperture stop during the zooming process so as to balance the image quality at each focal length of the image capturing lens system.

At least one lens group of the image capturing lens system can be moved along the optical axis so as to compensate temperature effect. Therefore, it is favorable for reducing the influence of temperature change on the image quality, so that the image capturing lens system is applicable to more applications. Moreover, the third lens group can be moved along the optical axis so as to compensate temperature effect. Therefore, it is favorable for minimizing the movement of lens groups.

At least one lens element in the first lens group, the second lens group, the third lens group and the fourth lens group can be made of plastic material. Therefore, it is favorable for reducing the system size and weight and increasing image quality and mass production. Moreover, there can be at least two lens elements in the first, second, third and fourth lens groups being made of plastic material. Moreover, there can be at least three lens elements in the first, second, third and fourth lens groups being made of plastic material. Moreover, there can be at least four lens elements in the first, second, third and fourth lens groups being made of plastic material.

At least one lens element in the second lens group, the third lens group and the fourth lens group has at least one inflection point in an off-axis region thereof. Therefore, it is favorable for increasing the shape variation of the lens element so as to miniaturize the lens element and improve image quality. Moreover, there can be at least two lens elements in the second, third and fourth lens groups each having at least one inflection point in an off-axis region thereof. Moreover, there can be at least three lens elements in the second, third and fourth lens groups each having at least one inflection point in an off-axis region thereof. Moreover, there can be at least four lens elements in the second, third and fourth lens groups each having at least one inflection point in an off-axis region thereof. Please refer to FIG. 25 , which shows a schematic view of the inflection points P of the eighth lens element 180 according to the 1st embodiment of the present disclosure. The inflection points of the eighth lens element in FIG. 25 are only exemplary. In each embodiment, each of object-side surfaces and image-side surfaces of the lens elements can have one or more inflection points in an off-axis region thereof.

At least one lens element in the second lens group, the third lens group and the fourth lens group can have at least one critical point in an off-axis region thereof. Therefore, it is favorable for further increasing the shape variation of the lens element so as to miniaturize the image capturing lens system and correct aberrations. Moreover, there can be at least two lens elements in the second, third and fourth lens groups each having at least one critical point in an off-axis region thereof. Please refer to FIG. 25 , which shows a schematic view of the critical point C of the eighth lens element 180 according to the 1st embodiment of the present disclosure. The critical point of the eighth lens element in FIG. 25 is only exemplary. In each embodiment, each of object-side surfaces and image-side surfaces of the lens elements can have one or more critical points in an off-axis region thereof.

The first lens element has positive refractive power. Therefore, it is favorable for reducing the outer diameter at the object side of the image capturing lens system.

The second lens element has negative refractive power. Therefore, it is favorable for balancing the refractive power at the object side of the image capturing lens system so as to reduce aberrations such as spherical aberration. The image-side surface of the second lens element can be concave in a paraxial region thereof. Therefore, it is favorable for adjusting the surface shape and refractive power of the second lens element so as to correct aberrations such as astigmatism.

The third lens element can have positive refractive power. Therefore, it is favorable for increasing the zoom ratio. The object-side surface of the third lens element can be convex in a paraxial region thereof. Therefore, it is favorable for adjusting light travelling direction so as to reduce the outer diameter of the image capturing lens system.

The fourth lens element can have negative refractive power. Therefore, it is favorable for correcting aberrations generated during the zooming process.

The fifth lens element can have positive refractive power. Therefore, it is favorable for maintaining the system size in the zooming process.

The seventh lens element can have negative refractive power. Therefore, it is favorable for balancing the refractive power at the image side of the image capturing lens system so as to reduce aberrations.

The eighth lens element can have positive refractive power. Therefore, it is favorable for adjusting the back focal length.

When an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, an Abbe number of the fifth lens element is V5, an Abbe number of the sixth lens element is V6, an Abbe number of the seventh lens element is V7, an Abbe number of the eighth lens element is V8, a refractive index of the first lens element is N1, a refractive index of the second lens element is N2, a refractive index of the third lens element is N3, a refractive index of the fourth lens element is N4, a refractive index of the fifth lens element is N5, a refractive index of the sixth lens element is N6, a refractive index of the seventh lens element is N7, a refractive index of the eighth lens element is N8, an Abbe number of one lens element of the image capturing lens system is Vi, a refractive index of the one lens element of the image capturing lens system is Ni, and a minimum value of Vi/Ni is (Vi/Ni) min, the following condition is satisfied: 7.5<(Vi/Ni) min<12.3, wherein i=1, 2, 3, 4, 5, 6, 7 or 8. Therefore, it is favorable for providing a proper lens material distribution of the image capturing lens system so as to reduce the system size and correct aberrations.

When half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, the following condition is satisfied: 3.0 degrees<HFOVS<25.0 degrees. Therefore, it is favorable for adjusting the viewing angle at the short-focal-length end so as to obtain a telephoto configuration for various applications. Moreover, the following condition can also be satisfied: 7.0 degrees<HFOVS<20.0 degrees. Moreover, the following condition can also be satisfied: 10.0 degrees<HFOVS<15.0 degrees.

When a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, and a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, the following condition is satisfied: 0.50<Y11L/Y82L<2.0. Therefore, it is favorable for adjusting light travelling direction so as to balance among the field of view, zoom ratio and image quality in the zooming process. Moreover, the following condition can also be satisfied: 0.65<Y11L/Y82L<1.5. Moreover, the following condition can also be satisfied: 0.75<Y11L/Y82L<1.3. Please refer to FIG. 26 , which shows a schematic view of Y11L and Y82L according to the 1st embodiment of the present disclosure. In addition, the image capturing lens system in FIG. 26 is at the long-focal-length end.

When a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, the following condition is satisfied: 0.50<Y11S/Y82S<2.0. Therefore, it is favorable for adjusting light travelling direction so as to balance among the field of view, zoom ratio and image quality in the zooming process. Moreover, the following condition can also be satisfied: 0.65<Y11S/Y82S<1.5. Moreover, the following condition can also be satisfied: 0.75<Y11S/Y82S<1.3. Please refer to FIG. 25 , which shows a schematic view of Y11S and Y82S according to the 1st embodiment of the present disclosure. In addition, the image capturing lens system in FIG. 25 is at the short-focal-length end.

When an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the long-focal-length end is TDL, and an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the short-focal-length end is TDS, the following condition can be satisfied: |TDL/TDS−1|<1.0E−2. Therefore, it is favorable for adjusting the lens elements distribution during the zooming process so as to simplify the structure of the image capturing lens system. Moreover, the following condition can also be satisfied: |TDL/TDS−1|<5.0E−3. Moreover, the following condition can also be satisfied: |TDL/TDS−1|<2.0E−3. Moreover, the following condition can also be satisfied: |TDL/TDS−1|<1.0E−3. Please refer to FIG. 25 and FIG. 26 , which respectively show a schematic view of TDS and a schematic view of TDL according to the 1st embodiment of the present disclosure.

When a focal length of the image capturing lens system at the long-focal-length end is fL, and a focal length of the image capturing lens system at the short-focal-length end is fS, the following condition can be satisfied: 1.45<fL/fS. Therefore, it is favorable for increasing the zoom ratio for more applications. Moreover, the following condition can also be satisfied: 1.95<fL/fS. Moreover, the following condition can also be satisfied: 2.45<fL/fS. Moreover, the following condition can also be satisfied: fL/fS<4.45. Therefore, it is favorable for preventing the zoom ratio from being overly large so as to ensure compact system size and high image quality. Moreover, the following condition can also be satisfied: fL/fS<3.50. Moreover, the following condition can also be satisfied: fL/fS<3.10. Moreover, the following condition can also be satisfied: 1.45<fL/fS<3.50.

When a variation of axial distance between the first lens group and the second lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG12, and an axial distance between a most object-side surface and a most image-side surface of the second lens group is TG2, the following condition can be satisfied: dTG12/TG2<−0.80. Therefore, it is favorable for the first lens group and the second lens group to collaborate with each other during the zooming process so as to increase the zoom ratio. Moreover, the following condition can also be satisfied: −3.0<dTG12/TG2<−1.0. Please refer to FIG. 26 , which shows a schematic view of TG2 according to the 1st embodiment of the present disclosure, wherein the most object-side surface of the second lens group G2 is the object-side surface 131 of the third lens element 130, and the most image-side surface of the second lens group G2 is the image-side surface 152 of the fifth lens element 150.

When a variation of axial distance between the third lens group and the fourth lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG34, an axial distance between a most object-side surface and a most image-side surface of the third lens group is TG3, and an axial distance between a most object-side surface and a most image-side surface of the fourth lens group is TG4, the following condition can be satisfied: |dTG34|/(TG3+TG4)<0.70. Therefore, it is favorable for the third lens group and the fourth lens group to collaborate with each other during the zooming process so as to correct aberrations generated during the zooming process. Please refer to FIG. 26 , which shows a schematic view of TG3 and TG4 according to the 1st embodiment of the present disclosure.

When an axial distance between a most object-side surface and a most image-side surface of the first lens group is TG1, and the axial distance between the most object-side surface and the most image-side surface of the second lens group is TG2, the following condition can be satisfied: 0.80<TG1/TG2<1.4. Therefore, it is favorable for adjusting the lens elements distribution of the first and second lens groups so as to reduce the outer diameter at the object side of the image capturing lens system. Please refer to FIG. 26 , which shows a schematic view of TG1 and TG2 according to the 1st embodiment of the present disclosure.

When the axial distance between the most object-side surface and the most image-side surface of the second lens group is TG2, and the axial distance between the most object-side surface and the most image-side surface of the third lens group is TG3, the following condition can be satisfied: 1.6<TG2/TG3<3.6. Therefore, it is favorable for adjusting the lens elements distribution so as to balance between the zoom ratio and the image quality.

When the axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the long-focal-length end is TDL, and the focal length of the image capturing lens system at the long-focal-length end is fL, the following condition can be satisfied: 0.50<TDL/fL<1.3. Therefore, it is favorable for balancing between the system size and viewing angle at the long-focal-length end. Moreover, the following condition can also be satisfied: 0.70<TDL/fL<1.1.

When the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, and a maximum image height of the image capturing lens system at the long-focal-length end (which may be half of a diagonal length of an effective photosensitive area of an image sensor) is ImgHL, the following condition can be satisfied: 0.65<Y11L/ImgHL<1.5. Therefore, it is favorable for adjusting light travelling direction in the zooming process so as to reduce the outer diameter of the image capturing lens system and obtain a telephoto configuration. Moreover, the following condition can also be satisfied: 0.75<Y11L/ImgHL<1.3. Please refer to FIG. 26 , which shows a schematic view of Y11L and ImgHL according to the 1st embodiment of the present disclosure.

When the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum image height of the image capturing lens system at the short-focal-length end (which may be half of the diagonal length of the effective photosensitive area of the image sensor) is ImgHS, the following condition can be satisfied: 0.65<Y11S/ImgHS<1.5. Therefore, it is favorable for adjusting light travelling direction in the zooming process so as to reduce the outer diameter of the image capturing lens system and obtain a telephoto configuration. Moreover, the following condition can also be satisfied: 0.75<Y11S/ImgHS<1.3. Please refer to FIG. 25 , which shows a schematic view of Y11S and ImgHS according to the 1st embodiment of the present disclosure.

When the Abbe number of the first lens element is V1, the Abbe number of the sixth lens element is V6, and the Abbe number of the eighth lens element is V8, the following condition can be satisfied: 30.0<V1+V6+V8<105.0. Therefore, a proper distribution of materials of the lens elements is favorable for correcting chromatic aberration. Moreover, the following condition can also be satisfied: 35.0<V1+V6+V8<85.0. Moreover, the following condition can also be satisfied: 40.0<V1+V6+V8<70.0.

When a focal length of the fourth lens element is f4, and a focal length of the fifth lens element is f5, the following condition can be satisfied: −1.0<f4/f5<−0.10. Therefore, it is favorable for balancing the refractive power distribution between the object side and the image side of the image capturing lens system so as to reduce the system size.

When the focal length of the image capturing lens system at the short-focal-length end is fS, and an entrance pupil diameter of the image capturing lens system at the short-focal-length end is EPDS, the following condition can be satisfied: 2.0<fS/EPDS<3.8. Therefore, it is favorable for balancing between the field of view and aperture size of the image capturing lens system at the short-focal-length end. Moreover, the following condition can also be satisfied: 2.5<fS/EPDS<3.5.

When the focal length of the image capturing lens system at the short-focal-length end is fS, a focal length of the first lens group is fG1, a focal length of the second lens group is fG2, a focal length of the third lens group is fG3, and a focal length of the fourth lens group is fG4, at least one of the following conditions can be satisfied: −1.5<fS/fG1<0; 1.0<fS/fG2<2.0; −1.2<fS/fG3<−0.50; or 0.30<fS/fG4<1.5. Therefore, it is favorable for adjusting the refractive power distribution of the image capturing lens system at the short-focal-length end so as to balance among the system size, field of view and image quality. Moreover, the following condition can also be satisfied: −1.0<fS/fG1<−0.55. Said focal length of one lens group is a composite focal length of all lens elements in the lens group.

When an axial distance between the image-side surface of the eighth lens element and an image surface when the image capturing lens system is at the long-focal-length end is BLL, and an axial distance between the image-side surface of the eighth lens element and the image surface when the image capturing lens system is at the short-focal-length end is BLS, the following condition can be satisfied: |BLL/BLS−1|<5.0E−2. Therefore, it is favorable for preventing the incident angle of light on the image surface from overly varying in the zooming process. Moreover, the following condition can also be satisfied: |BLL/BLS−1|<3.0E−2. Moreover, the following condition can also be satisfied: |BLL/BLS−1|<1.0E−2. Please refer to FIG. 25 and FIG. 26 , which respectively show a schematic view of BLS and a schematic view of BLL according to the 1st embodiment of the present disclosure.

When the axial distance between the most object-side surface and the most image-side surface of the third lens group is TG3, and the axial distance between the most object-side surface and the most image-side surface of the fourth lens group is TG4, the following condition can be satisfied: 0.35<TG3/TG4<3.0. Therefore, it is favorable for correcting aberrations generated during the zooming process and reducing the variation of back focal length. Moreover, the following condition can also be satisfied: 0.50<TG3/TG4<2.0.

When a focal length of the first lens element is f1, and a focal length of the third lens element is f3, the following condition can be satisfied: 0.60<f1/f3<6.0. Therefore, it is favorable for adjusting the refractive power distribution at the object side of the image capturing lens system so as to reduce the system size. Moreover, the following condition can also be satisfied: 1.0<f1/f3<3.0.

When half of a maximum field of view of the image capturing lens system at the long-focal-length end is HFOVL, the following condition can be satisfied: 3.0 degrees<HFOVL<10.0 degrees. Therefore, it is favorable for adjusting the field of view of the image capturing lens system at the long-focal-length end so as to obtain a telephoto configuration for various applications.

When the focal length of the first lens group is fG1, and the focal length of the second lens group is fG2, the following condition can be satisfied: −2.5<fG1/fG2<−1.5. Therefore, it is favorable for adjusting the refractive power distribution so as to increase zoom ratio.

When the focal length of the third lens group is fG3, and the focal length of the fourth lens group is fG4, the following condition can be satisfied: −1.2<fG3/fG4<−0.50. Therefore, it is favorable for adjusting the refractive power distribution so as to correct aberrations generated during the zooming process.

When the variation of axial distance between the first lens group and the second lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG12, and a variation of axial distance between the second lens group and the third lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG23, the following condition can be satisfied: −2.0<dTG12/dTG23<−0.50. Therefore, it is favorable for increasing the zoom ratio and ensuring consistent image quality in the zooming process. Moreover, the following condition can also be satisfied: −1.5<dTG12/dTG23<−0.70. Moreover, the following condition can also be satisfied: −1.2<dTG12/dTG23<−0.85.

According to the present disclosure, the aforementioned features and conditions can be utilized in numerous combinations so as to achieve corresponding effects.

According to the present disclosure, the lens elements of the image capturing lens system can be made of either glass or plastic material. When the lens elements are made of glass material, the refractive power distribution of the image capturing lens system may be more flexible, and the influence on imaging caused by external environment temperature change may be reduced. The glass lens element can either be made by grinding or molding. When the lens elements are made of plastic material, the manufacturing costs can be effectively reduced. Furthermore, surfaces of each lens element can be arranged to be spherical or aspheric. Spherical lens elements are simple in manufacture. Aspheric lens element design allows more control variables for eliminating aberrations thereof and reducing the required number of lens elements, and the total track length of the image capturing lens system can therefore be effectively shortened. Additionally, the aspheric surfaces may be formed by plastic injection molding or glass molding.

According to the present disclosure, when a lens surface is aspheric, it means that the lens surface has an aspheric shape throughout its optically effective area, or a portion(s) thereof.

According to the present disclosure, one or more of the lens elements' material may optionally include an additive which alters the lens elements' transmittance in a specific range of wavelength for a reduction in unwanted stray light or colour deviation. For example, the additive may optionally filter out light in the wavelength range of 600 nm to 800 nm to reduce excessive red light and/or near infrared light; or may optionally filter out light in the wavelength range of 350 nm to 450 nm to reduce excessive blue light and/or near ultraviolet light from interfering the final image. The additive may be homogeneously mixed with a plastic material to be used in manufacturing a mixed-material lens element by injection molding.

According to the present disclosure, each of an object-side surface and an image-side surface has a paraxial region and an off-axis region. The paraxial region refers to the region of the surface where light rays travel close to the optical axis, and the off-axis region refers to the region of the surface away from the paraxial region. Particularly, unless otherwise stated, when the lens element has a convex surface, it indicates that the surface is convex in the paraxial region thereof; when the lens element has a concave surface, it indicates that the surface is concave in the paraxial region thereof. Moreover, when a region of refractive power or focus of a lens element is not defined, it indicates that the region of refractive power or focus of the lens element is in the paraxial region thereof.

According to the present disclosure, an inflection point is a point on the surface of the lens element at which the surface changes from concave to convex, or vice versa. A critical point is a non-axial point of the lens surface where its tangent is perpendicular to the optical axis.

According to the present disclosure, the image surface of the image capturing lens system, based on the corresponding image sensor, can be flat or curved, especially a curved surface being concave facing towards the object side of the image capturing lens system.

According to the present disclosure, an image correction unit, such as a field flattener, can be optionally disposed between the lens element closest to the image side of the image capturing lens system along the optical path and the image surface for correction of aberrations such as field curvature. The optical properties of the image correction unit, such as curvature, thickness, index of refraction, position and surface shape (convex or concave surface with spherical, aspheric, diffractive or Fresnel types), can be adjusted according to the design of the image capturing unit. In general, a preferable image correction unit is, for example, a thin transparent element having a concave object-side surface and a planar image-side surface, and the thin transparent element is disposed near the image surface.

According to the present disclosure, at least one light-folding element can be optionally disposed between an imaged object and the image surface on the imaging optical path, such that the image capturing lens system can be more flexible in space arrangement, and therefore the dimensions of an electronic device is not restricted by the total track length of the image capturing lens system. Moreover, the at least one light-folding element can be disposed on the object side of the first lens element. Moreover, the at least one light-folding element can include at least one reflection mirror. Moreover, the at least one light-folding element can include at least one prism. Moreover, the prism can have refractive power, and the surface of the prism can include a non-planar surface, such as spherical surface, aspheric surface, concave surface or convex surface. Therefore, it is favorable for improving image quality. Specifically, please refer to FIG. 27 and FIG. 28 . FIG. 27 shows a schematic view of a configuration of a light-folding element in an image capturing lens system according to one embodiment of the present disclosure, and FIG. 28 shows a schematic view of another configuration of a light-folding element in an image capturing lens system according to one embodiment of the present disclosure. In FIG. 27 and FIG. 28 , the image capturing lens system can have, in order from an imaged object (not shown in figure) to an image surface IM along an optical path, a first optical axis OA1, a light-folding element LF and a second optical axis OA2. The light-folding element LF can be disposed between the imaged object and a lens group LG of the image capturing lens system as shown in FIG. 27 or disposed between a lens group LG of the image capturing lens system and the image surface IM as shown in FIG. 28 . Furthermore, please refer to FIG. 29 , which shows a schematic view of a configuration of two light-folding elements in an image capturing lens system according to one embodiment of the present disclosure. In FIG. 29 , the image capturing lens system can have, in order from an imaged object (not shown in figure) to an image surface IM along an optical path, a first optical axis OA1, a first light-folding element LF1, a second optical axis OA2, a second light-folding element LF2 and a third optical axis OA3. The first light-folding element LF1 is disposed between the imaged object and a lens group LG of the image capturing lens system, and the second light-folding element LF2 is disposed between the lens group LG of the image capturing lens system and the image surface IM. The image capturing lens system can be optionally provided with three or more light-folding elements, and the present disclosure is not limited to the type, amount and position of the light-folding elements of the embodiments disclosed in the aforementioned figures.

According to the present disclosure, the image capturing lens system can include at least one stop, such as an aperture stop, a glare stop or a field stop. Said glare stop or said field stop is set for eliminating the stray light and thereby improving image quality thereof.

According to the present disclosure, an aperture stop can be configured as a front stop or a middle stop. A front stop disposed between an imaged object and the first lens element can provide a longer distance between an exit pupil of the image capturing lens system and the image surface to produce a telecentric effect, and thereby improves the image-sensing efficiency of an image sensor (for example, CCD or CMOS). A middle stop disposed between the first lens element and the image surface is favorable for enlarging the viewing angle of the image capturing lens system and thereby provides a wider field of view for the same.

According to the present disclosure, the image capturing lens system can include an aperture control unit. The aperture control unit may be a mechanical component or a light modulator, which can control the size and shape of the aperture through electricity or electrical signals. The mechanical component can include a movable member, such as a blade assembly or a light shielding sheet. The light modulator can include a shielding element, such as a filter, an electrochromic material or a liquid-crystal layer. The aperture control unit controls the amount of incident light or exposure time to enhance the capability of image quality adjustment. In addition, the aperture control unit can be the aperture stop of the present disclosure, which changes the f-number to obtain different image effects, such as the depth of field or lens speed.

According to the present disclosure, the object side and image side are defined in accordance with the direction of the optical axis, and the axial optical data are calculated along the optical axis. Furthermore, if the optical axis is folded by a light-folding element, the axial optical data are also calculated along the folded optical axis.

According to the above description of the present disclosure, the following specific embodiments are provided for further explanation.

1st Embodiment

FIG. 1 is a schematic view of an image capturing unit at the short-focal-length end according to the 1st embodiment of the present disclosure. FIG. 2 is a schematic view of the image capturing unit at the long-focal-length end according to the 1st embodiment of the present disclosure. FIG. 3 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 1st embodiment. FIG. 4 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 1st embodiment. In FIG. 1 and FIG. 2 , the image capturing unit includes the image capturing lens system (its reference numeral is omitted) of the present disclosure and an image sensor 199. The image capturing lens system includes, in order from an object side to an image side along an optical path, a stop 101, a first lens element 110, a second lens element 120, a third lens element 130, an aperture stop 100, a fourth lens element 140, a fifth lens element 150, a sixth lens element 160, a seventh lens element 170, an eighth lens element 180, a filter 190 and an image surface 195. In addition, the image capturing lens system has a configuration of a first lens group G1 (including the first lens element 110 and the second lens element 120), a second lens group G2 (including the third lens element 130, the aperture stop 100, the fourth lens element 140 and the fifth lens element 150), a third lens group G3 (including the sixth lens element 160 and the seventh lens element 170) and a fourth lens group G4 (including the eighth lens element 180). The first lens group G1 has negative refractive power, the second lens group G2 has positive refractive power, the third lens group G3 has negative refractive power, and the fourth lens group G4 has positive refractive power. The image capturing lens system includes eight lens elements (110, 120, 130, 140, 150, 160, 170 and 180) with no additional lens element disposed between each of the adjacent eight lens elements.

The focal length of the image capturing lens system is varied by changing axial distances between the four lens groups (G1, G2, G3 and G4) in a zooming process. As shown in FIG. 1 and FIG. 2 , the second lens group G2 is moved relative to the first lens group G1 along an optical axis in the zooming process, and the third lens group G3 is moved relative to the first lens group G1 along the optical axis in the zooming process. Furthermore, the image capturing lens system has a short-focal-length end as shown in FIG. 1 and a long-focal-length end as shown in FIG. 2 . In addition, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group G2 is moved along the optical axis toward the object side relative to the first lens group G1. It is noted that there is no relative motion between lens elements of each of the four lens groups in the zooming process.

The first lens element 110 with positive refractive power has an object-side surface 111 being convex in a paraxial region thereof and an image-side surface 112 being convex in a paraxial region thereof. The first lens element 110 is made of plastic material and has the object-side surface 111 and the image-side surface 112 being both aspheric.

The second lens element 120 with negative refractive power has an object-side surface 121 being convex in a paraxial region thereof and an image-side surface 122 being concave in a paraxial region thereof. The second lens element 120 is made of plastic material and has the object-side surface 121 and the image-side surface 122 being both aspheric.

The third lens element 130 with positive refractive power has an object-side surface 131 being convex in a paraxial region thereof and an image-side surface 132 being convex in a paraxial region thereof. The third lens element 130 is made of glass material and has the object-side surface 131 and the image-side surface 132 being both aspheric. The third lens element 130 has at least one inflection point in an off-axis region thereof.

The fourth lens element 140 with negative refractive power has an object-side surface 141 being concave in a paraxial region thereof and an image-side surface 142 being convex in a paraxial region thereof. The fourth lens element 140 is made of plastic material and has the object-side surface 141 and the image-side surface 142 being both aspheric. The fourth lens element 140 has at least one inflection point and at least one critical point in an off-axis region thereof.

The fifth lens element 150 with positive refractive power has an object-side surface 151 being concave in a paraxial region thereof and an image-side surface 152 being convex in a paraxial region thereof. The fifth lens element 150 is made of plastic material and has the object-side surface 151 and the image-side surface 152 being both aspheric. The fifth lens element 150 has at least one inflection point and at least one critical point in an off-axis region thereof.

The sixth lens element 160 with positive refractive power has an object-side surface 161 being convex in a paraxial region thereof and an image-side surface 162 being concave in a paraxial region thereof. The sixth lens element 160 is made of plastic material and has the object-side surface 161 and the image-side surface 162 being both aspheric.

The seventh lens element 170 with negative refractive power has an object-side surface 171 being concave in a paraxial region thereof and an image-side surface 172 being concave in a paraxial region thereof. The seventh lens element 170 is made of plastic material and has the object-side surface 171 and the image-side surface 172 being both aspheric. The seventh lens element 170 has at least one inflection point and at least one critical point in an off-axis region thereof.

The eighth lens element 180 with positive refractive power has an object-side surface 181 being convex in a paraxial region thereof and an image-side surface 182 being concave in a paraxial region thereof. The eighth lens element 180 is made of plastic material and has the object-side surface 181 and the image-side surface 182 being both aspheric. The eighth lens element 180 has at least one inflection point and at least one critical point in an off-axis region thereof.

The filter 190 is made of glass material and located between the eighth lens element 180 and the image surface 195, and will not affect the focal length of the image capturing lens system. The image sensor 199 is disposed on or near the image surface 195.

The equation of the aspheric surface profiles of the aforementioned lens elements of the 1st embodiment is expressed as follows:

${{X(Y)} = {{\left( {Y^{2}/R} \right)/\left( {1 + {sqr{t\left( {1 - {\left( {1 + k} \right) \times \left( {Y/R} \right)^{2}}} \right)}}} \right)} + {\sum\limits_{i}{({Ai}) \times \left( Y^{i} \right)}}}},$ where,

X is a displacement in parallel with an optical axis from an axial vertex on the aspheric surface to a point at a distance of Y from the optical axis on the aspheric surface;

Y is the vertical distance from the point on the aspheric surface to the optical axis;

R is the curvature radius;

k is the conic coefficient; and

Ai is the i-th aspheric coefficient, and in the embodiments, i may be, but is not limited to, 4, 6, 8, 10, 12, 14 and 16.

In the image capturing lens system of the image capturing unit according to the 1st embodiment, a focal length of the image capturing lens system is f, an f-number of the image capturing lens system is Fno, half of a maximum field of view of the image capturing lens system is HFOV, an axial distance between an imaged object and the stop 101 is D0, an axial distance between the first lens group G1 and the second lens group G2 is D5, an axial distance between the second lens group G2 and the third lens group G3 is D12, and an axial distance between the third lens group G3 and the fourth lens group G4 is D16. With different focusing conditions, the aforementioned parameters may have different values. In this embodiment, two of various focusing states of the image capturing lens system according to different focusing conditions are provided (i.e., different object distances). A first focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at infinity, and a second focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at a finite distance.

Furthermore, in each focusing state, some of the aforementioned parameters have different values when the image capturing lens system is at the short-focal-length end or at the long-focal-length end. Specifically, a focal length of the image capturing lens system at the short-focal-length end is fS, a focal length of the image capturing lens system at the long-focal-length end is fL, an f-number of the image capturing lens system at the short-focal-length end is FnoS, an f-number of the image capturing lens system at the long-focal-length end is FnoL, half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, and half of a maximum field of view of the image capturing lens system at the long-focal-length end is HFOVL.

Note that FIG. 1 shows the image capturing lens system at the short-focal-length end in the first focusing state, and FIG. 2 shows the image capturing lens system at the long-focal-length end in the first focusing state.

In the first focusing state, when the image capturing lens system is at the short-focal-length end, the aforementioned parameters have the following values: fS=7.49 millimeters (mm), FnoS=3.21, HFOVS=13.8 degrees (deg.), D0=∞ (infinity), D5=5.432 mm, D12=1.803 mm, and D16=3.493 mm.

In the first focusing state, when the image capturing lens system is at the long-focal-length end, the aforementioned parameters have the following values: fL=18.75 mm, FnoL=5.16, HFOVL=5.5 degrees, D0=∞, D5=0.424 mm, D12=6.688 mm, and D16=3.616 mm.

When an Abbe number of the first lens element 110 is V1, an Abbe number of the second lens element 120 is V2, an Abbe number of the third lens element 130 is V3, an Abbe number of the fourth lens element 140 is V4, an Abbe number of the fifth lens element 150 is V5, an Abbe number of the sixth lens element 160 is V6, an Abbe number of the seventh lens element 170 is V7, an Abbe number of the eighth lens element 180 is V8, an Abbe number of the i-th lens element is Vi, a refractive index of the first lens element 110 is N1, a refractive index of the second lens element 120 is N2, a refractive index of the third lens element 130 is N3, a refractive index of the fourth lens element 140 is N4, a refractive index of the fifth lens element 150 is N5, a refractive index of the sixth lens element 160 is N6, a refractive index of the seventh lens element 170 is N7, a refractive index of the eighth lens element 180 is N8, a refractive index of the i-th lens element is Ni, and a minimum value of Vi/Ni is (Vi/Ni) min, the following condition is satisfied: (Vi/Ni) min=8.70, wherein i=1, 2, 3, 4, 5, 6, 7 or 8. In this embodiment, among the first through eighth lens elements (110-180), a ratio of the Abbe number and the refractive index of the sixth lens element 160 is smaller than that of the other lens elements, and (Vi/Ni) min is equal to the ratio of the Abbe number and the refractive index of the sixth lens element 160.

When the Abbe number of the first lens element 110 is V1, the Abbe number of the sixth lens element 160 is V6, and the Abbe number of the eighth lens element 180 is V8, the following condition is satisfied: V1+V6+V8=52.6.

When an axial distance between the object-side surface 111 of the first lens element 110 and the image-side surface 182 of the eighth lens element 180 when the image capturing lens system is at the long-focal-length end is TDL, and the focal length of the image capturing lens system at the long-focal-length end is fL, the following condition is satisfied: TDL/fL=0.92.

When an axial distance between the image-side surface 182 of the eighth lens element 180 and the image surface 195 when the image capturing lens system is at the long-focal-length end is BLL, and an axial distance between the image-side surface 182 of the eighth lens element 180 and the image surface 195 when the image capturing lens system is at the short-focal-length end is BLS, the following condition is satisfied: |BLL/BLS−1|=0.00E+00.

When a variation of axial distance between the third lens group G3 and the fourth lens group G4 when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG34, an axial distance between a most object-side surface and a most image-side surface of the third lens group G3 is TG3, and an axial distance between a most object-side surface and a most image-side surface of the fourth lens group G4 is TG4, the following condition is satisfied: |dTG34|/(TG3+TG4)=0.07. In this embodiment, dTG34=3.616-3.493=0.123 (mm).

When the axial distance between the object-side surface 111 of the first lens element 110 and the image-side surface 182 of the eighth lens element 180 when the image capturing lens system is at the long-focal-length end is TDL, and an axial distance between the object-side surface 111 of the first lens element 110 and the image-side surface 182 of the eighth lens element 180 when the image capturing lens system is at the short-focal-length end is TDS, the following condition is satisfied: |TDL/TDS−1|=0.00E+00.

When a variation of axial distance between the first lens group G1 and the second lens group G2 when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG12, and a variation of axial distance between the second lens group G2 and the third lens group G3 when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG23, the following condition is satisfied: dTG12/dTG23=−1.03. In this embodiment, dTG12=0.424−5.432=−5.008 (mm), and dTG23=6.688−1.803=4.885 (mm).

When the variation of axial distance between the first lens group G1 and the second lens group G2 when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG12, and an axial distance between a most object-side surface and a most image-side surface of the second lens group G2 is TG2, the following condition is satisfied: dTG12/TG2=−2.38.

When an axial distance between a most object-side surface and a most image-side surface of the first lens group G1 is TG1, and the axial distance between the most object-side surface and the most image-side surface of the second lens group G2 is TG2, the following condition is satisfied: TG1/TG2=1.21.

When the axial distance between the most object-side surface and the most image-side surface of the second lens group G2 is TG2, and the axial distance between the most object-side surface and the most image-side surface of the third lens group G3 is TG3, the following condition is satisfied: TG2/TG3=1.84.

When the axial distance between the most object-side surface and the most image-side surface of the third lens group G3 is TG3, and the axial distance between the most object-side surface and the most image-side surface of the fourth lens group G4 is TG4, the following condition is satisfied: TG3/TG4=1.66.

When a focal length of the first lens element 110 is f1, and a focal length of the third lens element 130 is f3, the following condition is satisfied: f1/f3=2.19.

When a focal length of the fourth lens element 140 is f4, and a focal length of the fifth lens element 150 is f5, the following condition is satisfied: f4/f5=−0.52.

When a focal length of the first lens group G1 is fG1, and a focal length of the second lens group G2 is fG2, the following condition is satisfied: fG1/fG2=−1.84.

When a focal length of the third lens group G3 is fG3, and a focal length of the fourth lens group G4 is fG4, the following condition is satisfied: fG3/fG4=−0.87.

When the focal length of the image capturing lens system at the long-focal-length end is fL, and the focal length of the image capturing lens system at the short-focal-length end is fS, the following condition is satisfied: fL/fS=2.50.

When the focal length of the image capturing lens system at the short-focal-length end is fS, and an entrance pupil diameter of the image capturing lens system at the short-focal-length end is EPDS, the following condition is satisfied: fS/EPDS=3.21.

When the focal length of the image capturing lens system at the short-focal-length end is fS, the focal length of the first lens group G1 is fG1, the focal length of the second lens group G2 is fG2, the focal length of the third lens group G3 is fG3, and the focal length of the fourth lens group G4 is fG4, the following conditions are satisfied: fS/fG1=−0.77; fS/fG2=1.42; fS/fG3=−0.71; and fS/fG4=0.62.

When half of the maximum field of view of the image capturing lens system at the long-focal-length end is HFOVL, the following condition is satisfied: HFOVL=5.5 degrees.

When half of the maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, the following condition is satisfied: HFOVS=13.8 degrees.

When a maximum distance between an optically effective area of the object-side surface 111 of the first lens element 110 and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, and a maximum image height of the image capturing lens system at the long-focal-length end is ImgHL, the following condition is satisfied: Y11L/ImgHL=1.16.

When the maximum distance between the optically effective area of the object-side surface 111 of the first lens element 110 and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, and a maximum distance between an optically effective area of the image-side surface 182 of the eighth lens element 180 and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, the following condition is satisfied: Y11L/Y82L=1.08.

When a maximum distance between an optically effective area of the object-side surface 111 of the first lens element 110 and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum image height of the image capturing lens system at the short-focal-length end is ImgHS, the following condition is satisfied: Y11S/ImgHS=1.21.

When the maximum distance between the optically effective area of the object-side surface 111 of the first lens element 110 and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, and a maximum distance between an optically effective area of the image-side surface 182 of the eighth lens element 180 and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, the following condition is satisfied: Y11S/Y82S=1.13.

The detailed optical data of the 1st embodiment are shown in Table 1 and Table 2, and the aspheric surface data are shown in Table 3 below.

TABLE 1 1st Embodiment Surface # Curvature Radius Thickness Material Index Abbe # Focal Length 0 Object Plano D0  1 Stop Plano −0.490  2 Lens 1 6.370 (ASP) 1.500 Plastic 1.669 19.5 8.56 3 −51.502 (ASP) 0.485 4 Lens 2 263.154 (ASP) 0.559 Plastic 1.582 30.2 −3.67 5 2.120 (ASP) D5  6 Lens 3 3.210 (ASP) 1.050 Glass 1.542 62.9 3.91 7 −5.536 (ASP) −0.132  8 Ape. Stop Plano 0.162 9 Lens 4 −4.267 (ASP) 0.300 Plastic 1.614 26.0 −7.14 10 −163.820 (ASP) 0.182 11 Lens 5 −500.000 (ASP) 0.544 Plastic 1.529 58.0 13.75 12 −7.171 (ASP) D12 13 Lens 6 6.344 (ASP) 0.675 Plastic 1.701 14.8 19.33 14 11.406 (ASP) 0.170 15 Lens 7 −4.584 (ASP) 0.300 Plastic 1.614 26.0 −6.47 16 30.485 (ASP) D16 17 Lens 8 4.706 (ASP) 0.691 Plastic 1.686 18.4 12.11 18 10.204 (ASP) 0.500 19 Filter Plano 0.210 Glass 1.517 64.2 — 20 Plano 2.077 21 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). An effective radius of the stop 101 (Surface 1) is 2.200 mm.

In Table 1, the curvature radius, the thickness and the focal length are shown in millimeters (mm). Surface numbers 0-21 represent the surfaces sequentially arranged from the object side to the image side along the optical axis.

The rest optical data of the image capturing lens system, including in the second focusing state, are disclosed in Table 2 below. Also, the definitions of the parameters shown in Table 2 are consistent with those stated in the first focusing state. In addition, it can be known from Table 2 that when the object distance decreases in the focusing process (e.g., from the first focusing state to the second focusing state), the axial distance between the first lens group G1 and the third lens group G3 increases from 9.341 mm (at short-focal-length end) and 9.218 mm (at long-focal-length end) of the first focusing state to 9.401 mm (at short-focal-length end) and 9.584 mm (at long-focal-length end) of the second focusing state; that is, when the object distance decreases in the focusing process, the third lens group G3 is moved along the optical axis toward the image side relative to the first lens group G1 in the focusing process.

TABLE 2 1st Embodiment Short-focal-length End Long-focal-length End First Focusing State f [mm] 7.49 18.75 Fno 3.21 5.16 HFOV [deg.] 13.8 5.5 D0 [mm] ∞ ∞ D5 [mm] 5.432 0.424 D12 [mm] 1.803 6.688 D16 [mm] 3.493 3.616 Second Focusing State Fno 3.21 5.14 HFOV [deg.] 13.8 5.5 D0 [mm] 1000.000 1000.000 D5 [mm] 5.432 0.424 D12 [mm] 1.863 7.054 D16 [mm] 3.432 3.250 (Vi/Ni)min 8.70 fG3/fG4 −0.87 V1 + V6 + V8 52.6 fL/fS 2.50 TDL/fL 0.92 fS/EPDS 3.21 |BLL/BLS − 1| 0.00E+00 fS/fG1 −0.77 |dTG34|/(TG3 + TG4) 0.07 fS/fG2 1.42 |TDL/TDS − 1| 0.00E+00 fS/fG3 −0.71 dTG12/dTG23 −1.03 fS/fG4 0.62 dTG12/TG2 −2.38 HFOVL [deg.] 5.5 TG1/TG2 1.21 HFOVS [deg.] 13.8 TG2/TG3 1.84 Y11L/ImgHL 1.16 TG3/TG4 1.66 Y11L/Y82L 1.08 f1/f3 2.19 Y11S/ImgHS 1.21 f4/f5 −0.52 Y11S/Y82S 1.13 fG1/fG2 −1.84 — —

TABLE 3 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 2.8650E+00 −9.0000E+01   4.5071E+01 −5.7401E+00 −1.1511E+01 0.0000E+00 A4 = 3.8184E−03 1.6754E−02 −4.2422E−02 −8.7581E−03  4.1829E−02 1.1687E−02 A6 = −5.2209E−04  −9.0875E−03  −1.5090E−03 −9.0931E−03 −1.8383E−02 6.6917E−03 A8 = 9.7466E−05 4.1213E−03  1.0686E−02  1.3699E−02  7.7725E−03 −8.0603E−03  A10 = 3.3665E−05 −8.0999E−04  −5.3013E−03 −7.3405E−03 −2.8920E−03 2.1062E−03 A12 = −1.0003E−05  4.0344E−05  1.1671E−03  1.8790E−03  6.3204E−04 −1.8451E−04  A14 = 9.7957E−07 8.1343E−06 −9.9563E−05 −1.9151E−04 −7.7254E−05 −5.9301E−06  Surface # 9 10 11 12 13 14 k = 0.0000E+00 0.0000E+00  0.0000E+00 0.0000E+00  1.7737E+00 0.0000E+00 A4 = 4.2516E−02 2.9888E−02 −7.7799E−03 6.3750E−04 −3.1334E−03 2.0093E−03 A6 = −3.0640E−03  6.4669E−03  2.4166E−02 7.9520E−03 −3.7873E−03 −5.3737E−03  A8 = −3.0546E−03  −9.4860E−03  −2.0810E−02 −6.4587E−03   2.1436E−03 1.3288E−03 A10 = 7.5238E−04 3.2961E−03  7.3704E−03 2.5038E−03 −2.8408E−03 3.3682E−07 A12 = — −3.7660E−04  −8.6328E−04 −2.8103E−04   2.1414E−03 7.5891E−05 A14 = — — — — −6.4275E−04 — A16 = — — — —  6.9962E−05 — Surface # 15 16 17 18 k = 0.0000E+00 −9.0000E+01  6.8300E−01 0.0000E+00 A4 = 1.0791E−01  9.3824E−02 −2.0244E−02 −2.1672E−02  A6 = −3.5285E−02  −2.2837E−02  1.3649E−03 5.5218E−04 A8 = 1.7403E−02  1.2206E−02 −7.8241E−04 9.7425E−04 A10 = −7.1486E−03  −5.4580E−03  7.7924E−04 −3.0023E−04  A12 = 1.1386E−03  1.3987E−03 −2.9297E−04 5.1522E−05 A14 = — −6.4657E−04  5.2109E−05 −5.1065E−06  A16 = —  1.6443E−04 −3.9488E−06 —

In Table 3, k represents the conic coefficient of the equation of the aspheric surface profiles. A4-A16 represent the aspheric coefficients ranging from the 4th order to the 16th order. The tables presented below for each embodiment are the corresponding schematic parameter and aberration curves, and the definitions of the tables are the same as Table 1 to Table 3 of the 1st embodiment. Therefore, an explanation in this regard will not be provided again.

2nd Embodiment

FIG. 5 is a schematic view of an image capturing unit at the short-focal-length end according to the 2nd embodiment of the present disclosure. FIG. 6 is a schematic view of the image capturing unit at the long-focal-length end according to the 2nd embodiment of the present disclosure. FIG. 7 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 2nd embodiment. FIG. 8 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 2nd embodiment. In FIG. 5 and FIG. 6 , the image capturing unit includes the image capturing lens system (its reference numeral is omitted) of the present disclosure and an image sensor 299. The image capturing lens system includes, in order from an object side to an image side along an optical path, a stop 201, a first lens element 210, a second lens element 220, a third lens element 230, an aperture stop 200, a fourth lens element 240, a fifth lens element 250, a sixth lens element 260, a seventh lens element 270, an eighth lens element 280, a filter 290 and an image surface 295. In addition, the image capturing lens system has a configuration of a first lens group G1 (including the first lens element 210 and the second lens element 220), a second lens group G2 (including the third lens element 230, the aperture stop 200, the fourth lens element 240 and the fifth lens element 250), a third lens group G3 (including the sixth lens element 260 and the seventh lens element 270) and a fourth lens group G4 (including the eighth lens element 280). The first lens group G1 has negative refractive power, the second lens group G2 has positive refractive power, the third lens group G3 has negative refractive power, and the fourth lens group G4 has positive refractive power. The image capturing lens system includes eight lens elements (210, 220, 230, 240, 250, 260, 270 and 280) with no additional lens element disposed between each of the adjacent eight lens elements.

The focal length of the image capturing lens system is varied by changing axial distances between the four lens groups (G1, G2, G3 and G4) in a zooming process. As shown in FIG. 5 and FIG. 6 , the second lens group G2 is moved relative to the first lens group G1 along an optical axis in the zooming process, and the third lens group G3 is moved relative to the first lens group G1 along the optical axis in the zooming process. Furthermore, the image capturing lens system has a short-focal-length end as shown in FIG. 5 and a long-focal-length end as shown in FIG. 6 . In addition, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group G2 is moved along the optical axis toward the object side relative to the first lens group G1. It is noted that there is no relative motion between lens elements of each of the four lens groups in the zooming process.

The first lens element 210 with positive refractive power has an object-side surface 211 being convex in a paraxial region thereof and an image-side surface 212 being concave in a paraxial region thereof. The first lens element 210 is made of plastic material and has the object-side surface 211 and the image-side surface 212 being both aspheric.

The second lens element 220 with negative refractive power has an object-side surface 221 being concave in a paraxial region thereof and an image-side surface 222 being concave in a paraxial region thereof. The second lens element 220 is made of plastic material and has the object-side surface 221 and the image-side surface 222 being both aspheric.

The third lens element 230 with positive refractive power has an object-side surface 231 being convex in a paraxial region thereof and an image-side surface 232 being convex in a paraxial region thereof. The third lens element 230 is made of plastic material and has the object-side surface 231 and the image-side surface 232 being both aspheric. The third lens element 230 has at least one inflection point in an off-axis region thereof.

The fourth lens element 240 with negative refractive power has an object-side surface 241 being concave in a paraxial region thereof and an image-side surface 242 being concave in a paraxial region thereof. The fourth lens element 240 is made of plastic material and has the object-side surface 241 and the image-side surface 242 being both aspheric. The fourth lens element 240 has at least one inflection point in an off-axis region thereof.

The fifth lens element 250 with positive refractive power has an object-side surface 251 being convex in a paraxial region thereof and an image-side surface 252 being convex in a paraxial region thereof. The fifth lens element 250 is made of glass material and has the object-side surface 251 and the image-side surface 252 being both spherical.

The sixth lens element 260 with positive refractive power has an object-side surface 261 being concave in a paraxial region thereof and an image-side surface 262 being convex in a paraxial region thereof. The sixth lens element 260 is made of plastic material and has the object-side surface 261 and the image-side surface 262 being both aspheric. The sixth lens element 260 has at least one inflection point and at least one critical point in an off-axis region thereof.

The seventh lens element 270 with negative refractive power has an object-side surface 271 being convex in a paraxial region thereof and an image-side surface 272 being concave in a paraxial region thereof. The seventh lens element 270 is made of plastic material and has the object-side surface 271 and the image-side surface 272 being both aspheric. The seventh lens element 270 has at least one inflection point and at least one critical point in an off-axis region thereof.

The eighth lens element 280 with positive refractive power has an object-side surface 281 being concave in a paraxial region thereof and an image-side surface 282 being convex in a paraxial region thereof. The eighth lens element 280 is made of plastic material and has the object-side surface 281 and the image-side surface 282 being both aspheric. The eighth lens element 280 has at least one inflection point and at least one critical point in an off-axis region thereof.

The filter 290 is made of glass material and located between the eighth lens element 280 and the image surface 295, and will not affect the focal length of the image capturing lens system. The image sensor 299 is disposed on or near the image surface 295.

In this embodiment, two of various focusing states of the image capturing lens system according to different focusing conditions are provided (i.e., different object distances). A first focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at infinity, and a second focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at a finite distance.

The detailed optical data of the 2nd embodiment are shown in Table 4 and Table 5, and the aspheric surface data are shown in Table 6 below.

TABLE 4 2nd Embodiment Surface # Curvature Radius Thickness Material Index Abbe # Focal Length 0 Object Plano D0  1 Stop Plano −0.540  2 Lens 1 6.011 (ASP) 1.500 Plastic 1.660 20.4 10.18 3 51.572 (ASP) 0.571 4 Lens 2 −128.493 (ASP) 0.446 Plastic 1.566 37.4 −4.03 5 2.325 (ASP) D5  6 Lens 3 3.487 (ASP) 1.050 Plastic 1.544 56.0 4.03 7 −5.273 (ASP) −0.130  8 Ape. Stop Plano 0.295 9 Lens 4 −3.775 (ASP) 0.415 Plastic 1.639 23.5 −5.69 10 100.000 (ASP) 0.200 11 Lens 5 24.321 (SPH) 0.900 Glass 1.569 56.1 7.73 12 −5.294 (SPH) D12 13 Lens 6 −7.323 (ASP) 0.453 Plastic 1.669 19.5 21.47 14 −4.971 (ASP) 0.132 15 Lens 7 10.698 (ASP) 0.323 Plastic 1.544 56.0 −7.11 16 2.812 (ASP) D16 17 Lens 8 −21.670 (ASP) 0.626 Plastic 1.669 19.5 16.02 18 −7.253 (ASP) 0.500 19 Filter Plano 0.210 Glass 1.517 64.2 — 20 Plano 2.035 21 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). An effective radius of the stop 201 (Surface 1) is 2.155 mm.

The definitions of these parameters shown in Table 5 are the same as those stated in the 1st embodiment with corresponding values for the 2nd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 4 and Table 6 as the following values and satisfy the following conditions:

TABLE 5 2nd Embodiment Short-focal-length End Long-focal-length End First Focusing State f [mm] 8.50 17.01 Fno 3.20 4.59 HFOV [deg.] 13.7 6.7 D0 [mm] ∞ ∞ D5 [mm] 4.017 0.419 D12 [mm] 2.71 5.477 D16 [mm] 2.533 3.365 Second Focusing State Fno 3.21 4.59 HFOV [deg.] 13.7 6.7 D0 [mm] 650.000 650.000 D5 [mm] 4.017 0.419 D12 [mm] 2.805 5.822 D16 [mm] 2.438 3.019 (Vi/Ni)min 11.65 fG3/fG4 −0.66 V1 + V6 + V8 59.3 fL/fS 2.00 TDL/fL 0.94 fS/EPDS 3.20 |BLL/BLS − 1| 0.00E+00 fS/fG1 −0.89 |dTG34|/(TG3 + TG4) 0.54 fS/fG2 1.67 |TDL/TDS − 1| 6.23E−05 fS/fG3 −0.81 dTG12/dTG23 −1.30 fS/fG4 0.53 dTG12/TG2 −1.32 HFOVL [deg.] 6.7 TG1/TG2 0.92 HFOVS [deg.] 13.7 TG2/TG3 3.01 Y11L/ImgHL 1.06 TG3/TG4 1.45 Y11L/Y82L 1.06 f1/f3 2.53 Y11S/ImgHS 1.06 f4/f5 −0.74 Y11S/Y82S 1.08 fG1/fG2 −1.88 — —

In the 2nd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment, so an explanation in this regard will not be provided again.

TABLE 6 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 2.3628E+00 1.0000E+01 −9.0000E+01 −6.9993E+00 −1.4952E+01 0.0000E+00 A4 = 4.3050E−03 2.0326E−02 −3.8362E−02 −7.1512E−03  4.2193E−02 1.5259E−02 A6 = −4.9796E−04  −8.3886E−03  −2.2768E−03 −1.1586E−02 −2.0262E−02 9.7553E−04 A8 = 1.2985E−04 3.7290E−03  1.0468E−02  1.3952E−02  9.1500E−03 −2.1317E−03  A10 = 1.0610E−05 −7.8894E−04  −5.3907E−03 −6.8411E−03 −3.1932E−03 2.6338E−04 A12 = −5.6807E−06  5.6206E−05  1.2324E−03  1.6316E−03  6.2960E−04 2.7273E−05 A14 = 6.5353E−07 4.7824E−06 −1.0924E−04 −1.5480E−04 −6.1562E−05 −9.8413E−06  Surface # 9 10 13 14 15 16 k = 0.0000E+00 0.0000E+00 −7.4029E+01  0.0000E+00  0.0000E+00 −1.2717E+01 A4 = 4.7011E−02 3.5676E−02 6.0107E−03 1.0029E−02 −1.4465E−01 −6.6613E−02 A6 = −9.2826E−03  −8.4418E−03  3.6254E−03 8.2184E−03  9.6340E−02  5.0861E−02 A8 = 7.9814E−04 1.9214E−03 2.0804E−03 3.1008E−03 −3.8421E−02 −2.3130E−02 A10 = 6.8684E−05 −1.8055E−04  −1.5719E−03  −3.8155E−03   7.2091E−03  5.6557E−03 A12 = — 2.5893E−07 1.5092E−04 7.7594E−04 −3.3564E−04 −3.8650E−04 A14 = — — 6.5861E−05 — — −6.7100E−05 A16 = — — −1.2478E−05  — —  8.4265E−06 Surface # 17 18 k = −1.6429E+01 0.0000E+00 A4 =  7.9378E−03 9.0643E−03 A6 =  1.0603E−03 2.1835E−04 A8 = −1.1309E−03 −2.7320E−04  A10 =  4.0079E−04 −2.9050E−05  A12 = −9.9519E−05 1.6309E−05 A14 =  1.4819E−05 −1.8383E−06  A16 = −1.0232E−06 —

3rd Embodiment

FIG. 9 is a schematic view of an image capturing unit at the short-focal-length end according to the 3rd embodiment of the present disclosure. FIG. 10 is a schematic view of the image capturing unit at the long-focal-length end according to the 3rd embodiment of the present disclosure. FIG. 11 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 3rd embodiment. FIG. 12 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 3rd embodiment. In FIG. 9 and FIG. 10 , the image capturing unit includes the image capturing lens system (its reference numeral is omitted) of the present disclosure and an image sensor 399. The image capturing lens system includes, in order from an object side to an image side along an optical path, a stop 301, a first lens element 310, a second lens element 320, a third lens element 330, an aperture stop 300, a fourth lens element 340, a fifth lens element 350, a sixth lens element 360, a seventh lens element 370, an eighth lens element 380, a filter 390 and an image surface 395. In addition, the image capturing lens system has a configuration of a first lens group G1 (including the first lens element 310 and the second lens element 320), a second lens group G2 (including the third lens element 330, the aperture stop 300, the fourth lens element 340 and the fifth lens element 350), a third lens group G3 (including the sixth lens element 360 and the seventh lens element 370) and a fourth lens group G4 (including the eighth lens element 380). The first lens group G1 has negative refractive power, the second lens group G2 has positive refractive power, the third lens group G3 has negative refractive power, and the fourth lens group G4 has positive refractive power. The image capturing lens system includes eight lens elements (310, 320, 330, 340, 350, 360, 370 and 380) with no additional lens element disposed between each of the adjacent eight lens elements.

The focal length of the image capturing lens system is varied by changing axial distances between the four lens groups (G1, G2, G3 and G4) in a zooming process. As shown in FIG. 9 and FIG. 10 , the second lens group G2 is moved relative to the first lens group G1 along an optical axis in the zooming process, and the third lens group G3 is moved relative to the first lens group G1 along the optical axis in the zooming process. Furthermore, the image capturing lens system has a short-focal-length end as shown in FIG. 9 and a long-focal-length end as shown in FIG. 10 . In addition, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group G2 is moved along the optical axis toward the object side relative to the first lens group G1. It is noted that there is no relative motion between lens elements of each of the four lens groups in the zooming process.

The first lens element 310 with positive refractive power has an object-side surface 311 being convex in a paraxial region thereof and an image-side surface 312 being convex in a paraxial region thereof. The first lens element 310 is made of plastic material and has the object-side surface 311 and the image-side surface 312 being both aspheric.

The second lens element 320 with negative refractive power has an object-side surface 321 being concave in a paraxial region thereof and an image-side surface 322 being concave in a paraxial region thereof. The second lens element 320 is made of plastic material and has the object-side surface 321 and the image-side surface 322 being both aspheric.

The third lens element 330 with positive refractive power has an object-side surface 331 being convex in a paraxial region thereof and an image-side surface 332 being convex in a paraxial region thereof. The third lens element 330 is made of plastic material and has the object-side surface 331 and the image-side surface 332 being both aspheric. The third lens element 330 has at least one inflection point in an off-axis region thereof.

The fourth lens element 340 with negative refractive power has an object-side surface 341 being concave in a paraxial region thereof and an image-side surface 342 being concave in a paraxial region thereof. The fourth lens element 340 is made of plastic material and has the object-side surface 341 and the image-side surface 342 being both aspheric. The fourth lens element 340 has at least one inflection point and at least one critical point in an off-axis region thereof.

The fifth lens element 350 with positive refractive power has an object-side surface 351 being convex in a paraxial region thereof and an image-side surface 352 being convex in a paraxial region thereof. The fifth lens element 350 is made of glass material and has the object-side surface 351 and the image-side surface 352 being both spherical.

The sixth lens element 360 with negative refractive power has an object-side surface 361 being concave in a paraxial region thereof and an image-side surface 362 being convex in a paraxial region thereof. The sixth lens element 360 is made of plastic material and has the object-side surface 361 and the image-side surface 362 being both aspheric. The sixth lens element 360 has at least one inflection point and at least one critical point in an off-axis region thereof.

The seventh lens element 370 with negative refractive power has an object-side surface 371 being concave in a paraxial region thereof and an image-side surface 372 being convex in a paraxial region thereof. The seventh lens element 370 is made of plastic material and has the object-side surface 371 and the image-side surface 372 being both aspheric. The seventh lens element 370 has at least one inflection point and at least one critical point in an off-axis region thereof.

The eighth lens element 380 with positive refractive power has an object-side surface 381 being convex in a paraxial region thereof and an image-side surface 382 being convex in a paraxial region thereof. The eighth lens element 380 is made of plastic material and has the object-side surface 381 and the image-side surface 382 being both aspheric. The eighth lens element 380 has at least one inflection point in an off-axis region thereof.

The filter 390 is made of glass material and located between the eighth lens element 380 and the image surface 395, and will not affect the focal length of the image capturing lens system. The image sensor 399 is disposed on or near the image surface 395.

In this embodiment, two of various focusing states of the image capturing lens system according to different focusing conditions are provided. A first focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at infinity, and a second focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at a finite distance.

The detailed optical data of the 3rd embodiment are shown in Table 7 and Table 8, and the aspheric surface data are shown in Table 9 below.

TABLE 7 3rd Embodiment Surface # Curvature Radius Thickness Material Index Abbe # Focal Length 0 Object Plano D0  1 Stop Plano −0.524  2 Lens 1 6.663 (ASP) 1.500 Plastic 1.660 20.4 6.43 3 −10.629 (ASP) 0.492 4 Lens 2 −13.687 (ASP) 0.548 Plastic 1.587 28.3 −3.06 5 2.100 (ASP) D5  6 Lens 3 3.245 (ASP) 1.050 Plastic 1.544 56.0 4.00 7 −5.840 (ASP) −0.130  8 Ape. Stop Plano 0.193 9 Lens 4 −7.086 (ASP) 0.571 Plastic 1.639 23.5 −6.26 10 9.458 (ASP) 0.172 11 Lens 5 7.976 (SPH) 0.868 Glass 1.804 46.6 9.56 12 −200.000 (SPH) D12 13 Lens 6 −9.026 (ASP) 0.320 Plastic 1.669 19.5 −124.26 14 −10.269 (ASP) 0.171 15 Lens 7 −4.372 (ASP) 0.320 Plastic 1.544 56.0 −9.96 16 −23.212 (ASP) D16 17 Lens 8 16.970 (ASP) 0.800 Plastic 1.669 19.5 10.34 18 −11.465 (ASP) 0.500 19 Filter Plano 0.210 Glass 1.517 64.2 — 20 Plano 2.675 21 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). An effective radius of the stop 301 (Surface 1) is 2.200 mm.

As shown in Table 8 below, in each focusing state, three different zooming states between the short-focal-length end and the long-focal-length end of the image capturing lens system and corresponding optical data are also disclosed in this embodiment. The definitions of these parameters shown in Table 8 are the same as those stated in the 1st embodiment with corresponding values for the 3rd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 7 and Table 9 as the following values and satisfy the following conditions:

TABLE 8 3rd Embodiment Short-focal- Long-focal- length End length End First Focusing State f [mm] 8.50 11.05 12.75 14.44 17.00 Fno 3.20 3.70 3.99 4.26 4.61 HFOV [deg.] 13.7 10.4 9.0 7.9 6.7 D0 [mm] ∞ ∞ ∞ ∞ ∞ D5 [mm] 4.144 2.729 1.997 1.381 0.588 D12 [mm] 2.536 3.192 3.785 4.496 5.872 D16 [mm] 2.047 2.806 2.945 2.850 2.267 Second Focusing State Fno 3.21 3.71 4.00 4.27 4.62 HFOV [deg.] 13.6 10.4 9.0 7.9 6.7 D0 [mm] 800.000 800.000 800.000 800.000 800.000 D5 [mm] 4.144 2.729 1.997 1.381 0.588 D12 [mm] 2.608 3.302 3.928 4.683 6.162 D16 [mm] 1.975 2.696 2.802 2.663 1.977 (Vi/Ni)min 11.65 fG3/fG4 −0.88 V1 + V6 + V8 59.3 fL/fS 2.00 TDL/fL 0.92 fS/EPDS 3.20 |BLL/BLS − 1| 0.00E+00 fS/fG1 −0.87 |dTG34|/(TG3 + TG4) 0.14 fS/fG2 1.70 |TDL/TDS − 1| 0.00E+00 fS/fG3 −0.94 dTG12/dTG23 −1.07 fS/fG4 0.82 dTG12/TG2 −1.31 HFOVL [deg.] 6.7 TG1/TG2 0.93 HFOVS [deg.] 13.7 TG2/TG3 3.36 Y11L/ImgHL 1.08 TG3/TG4 1.01 Y11L/Y82L 1.03 f1/f3 1.61 Y11S/ImgHS 1.08 f4/f5 −0.65 Y11S/Y82S 1.04 fG1/fG2 −1.96 — —

In the 3rd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment, so an explanation in this regard will not be provided again.

TABLE 9 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 2.1935E+00 −2.0612E+01   1.7056E+01 −5.4098E+00 −1.1537E+01 0.0000E+00 A4 = 4.4154E−03 2.0388E−02 −3.0966E−02 −8.9774E−03  3.8911E−02 2.7193E−02 A6 = −3.8619E−04  −1.0507E−02  −4.5733E−03 −5.9679E−03 −1.7419E−02 −2.2117E−02  A8 = 3.7519E−05 4.4353E−03  1.0856E−02  1.0058E−02  7.5638E−03 1.1673E−02 A10 = 6.4082E−05 −9.6337E−04  −5.3912E−03 −5.4907E−03 −2.8366E−03 −3.5164E−03  A12 = −1.7463E−05  7.9005E−05  1.2284E−03  1.4205E−03  6.8549E−04 4.7226E−04 A14 = 1.7042E−06 3.0152E−06 −1.0865E−04 −1.4464E−04 −8.3490E−05 −2.6450E−05  Surface # 9 10 13 14 15 16 k = 0.0000E+00 0.0000E+00 1.7955E+01  0.0000E+00 0.0000E+00 −4.1464E+01 A4 = 4.6220E−02 2.7976E−02 −2.3108E−02  −1.2458E−02 1.0722E−01  8.6139E−02 A6 = −2.6525E−02  −6.5608E−03  7.2911E−03 −1.2726E−02 −9.0478E−02  −5.6130E−02 A8 = 1.3811E−02 3.5088E−03 1.0106E−02  1.8896E−02 4.0764E−02  1.7426E−02 A10 = −3.9519E−03  −1.0811E−03  −5.9084E−03  −6.4197E−03 −9.7072E−03  −1.8728E−03 A12 = 4.3620E−04 1.2800E−04 1.4204E−03  7.4963E−04 9.4400E−04 −3.9848E−04 A14 = — — −1.7231E−04  — —  1.2278E−04 A16 = — — 1.1451E−05 — — −7.8019E−06 Surface # 17 18 k = −2.1318E+01 0.0000E+00 A4 =  5.2440E−03 4.4501E−03 A6 = −1.4389E−03 −1.2751E−03  A8 =  8.7371E−05 1.0078E−04 A10 =  2.5108E−05 −8.7330E−06  A12 = −1.2739E−05 7.7728E−09 A14 =  1.9520E−06 −1.3898E−07  A16 = −1.4324E−07 —

4th Embodiment

FIG. 13 is a schematic view of an image capturing unit at the short-focal-length end according to the 4th embodiment of the present disclosure. FIG. 14 is a schematic view of the image capturing unit at the long-focal-length end according to the 4th embodiment of the present disclosure. FIG. 15 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 4th embodiment. FIG. 16 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 4th embodiment. In FIG. 13 and FIG. 14 , the image capturing unit includes the image capturing lens system (its reference numeral is omitted) of the present disclosure and an image sensor 499. The image capturing lens system includes, in order from an object side to an image side along an optical path, a stop 401, a first lens element 410, a second lens element 420, a third lens element 430, an aperture stop 400, a fourth lens element 440, a fifth lens element 450, a sixth lens element 460, a seventh lens element 470, an eighth lens element 480, a filter 490 and an image surface 495. In addition, the image capturing lens system has a configuration of a first lens group G1 (including the first lens element 410 and the second lens element 420), a second lens group G2 (including the third lens element 430, the aperture stop 400, the fourth lens element 440 and the fifth lens element 450), a third lens group G3 (including the sixth lens element 460 and the seventh lens element 470) and a fourth lens group G4 (including the eighth lens element 480). The first lens group G1 has negative refractive power, the second lens group G2 has positive refractive power, the third lens group G3 has negative refractive power, and the fourth lens group G4 has positive refractive power. The image capturing lens system includes eight lens elements (410, 420, 430, 440, 450, 460, 470 and 480) with no additional lens element disposed between each of the adjacent eight lens elements.

The focal length of the image capturing lens system is varied by changing axial distances between the four lens groups (G1, G2, G3 and G4) in a zooming process. As shown in FIG. 13 and FIG. 14 , the second lens group G2 is moved relative to the first lens group G1 along an optical axis in the zooming process, and the third lens group G3 is moved relative to the first lens group G1 along the optical axis in the zooming process. Furthermore, the image capturing lens system has a short-focal-length end as shown in FIG. 13 and a long-focal-length end as shown in FIG. 14 . In addition, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group G2 is moved along the optical axis toward the object side relative to the first lens group G1. It is noted that there is no relative motion between lens elements of each of the four lens groups in the zooming process.

The first lens element 410 with positive refractive power has an object-side surface 411 being convex in a paraxial region thereof and an image-side surface 412 being convex in a paraxial region thereof. The first lens element 410 is made of plastic material and has the object-side surface 411 and the image-side surface 412 being both aspheric.

The second lens element 420 with negative refractive power has an object-side surface 421 being concave in a paraxial region thereof and an image-side surface 422 being concave in a paraxial region thereof. The second lens element 420 is made of plastic material and has the object-side surface 421 and the image-side surface 422 being both aspheric.

The third lens element 430 with positive refractive power has an object-side surface 431 being convex in a paraxial region thereof and an image-side surface 432 being convex in a paraxial region thereof. The third lens element 430 is made of plastic material and has the object-side surface 431 and the image-side surface 432 being both aspheric. The third lens element 430 has at least one inflection point in an off-axis region thereof.

The fourth lens element 440 with negative refractive power has an object-side surface 441 being concave in a paraxial region thereof and an image-side surface 442 being concave in a paraxial region thereof. The fourth lens element 440 is made of plastic material and has the object-side surface 441 and the image-side surface 442 being both aspheric. The fourth lens element 440 has at least one inflection point and at least one critical point in an off-axis region thereof.

The fifth lens element 450 with positive refractive power has an object-side surface 451 being convex in a paraxial region thereof and an image-side surface 452 being convex in a paraxial region thereof. The fifth lens element 450 is made of plastic material and has the object-side surface 451 and the image-side surface 452 being both aspheric. The fifth lens element 450 has at least one inflection point and at least one critical point in an off-axis region thereof.

The sixth lens element 460 with positive refractive power has an object-side surface 461 being concave in a paraxial region thereof and an image-side surface 462 being convex in a paraxial region thereof. The sixth lens element 460 is made of plastic material and has the object-side surface 461 and the image-side surface 462 being both aspheric. The sixth lens element 460 has at least one inflection point in an off-axis region thereof.

The seventh lens element 470 with negative refractive power has an object-side surface 471 being concave in a paraxial region thereof and an image-side surface 472 being convex in a paraxial region thereof. The seventh lens element 470 is made of plastic material and has the object-side surface 471 and the image-side surface 472 being both aspheric. The seventh lens element 470 has at least one inflection point and at least one critical point in an off-axis region thereof.

The eighth lens element 480 with positive refractive power has an object-side surface 481 being convex in a paraxial region thereof and an image-side surface 482 being convex in a paraxial region thereof. The eighth lens element 480 is made of plastic material and has the object-side surface 481 and the image-side surface 482 being both aspheric. The eighth lens element 480 has at least one inflection point in an off-axis region thereof.

The filter 490 is made of glass material and located between the eighth lens element 480 and the image surface 495, and will not affect the focal length of the image capturing lens system. The image sensor 499 is disposed on or near the image surface 495.

In this embodiment, two of various focusing states of the image capturing lens system according to different focusing conditions are provided. A first focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at infinity, and a second focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at a finite distance.

The detailed optical data of the 4th embodiment are shown in Table 10 and Table 11, and the aspheric surface data are shown in Table 12 below.

TABLE 10 4th Embodiment Surface # Curvature Radius Thickness Material Index Abbe # Focal Length 0 Object Plano D0  1 Stop Plano −0.558  2 Lens 1 6.038 (ASP) 1.500 Plastic 1.660 20.4 6.15 3 −11.165 (ASP) 0.356 4 Lens 2 −10.929 (ASP) 0.570 Plastic 1.587 28.3 −3.06 5 2.191 (ASP) D5  6 Lens 3 3.049 (ASP) 0.830 Plastic 1.544 56.0 4.47 7 −10.888 (ASP) 0.008 8 Ape. Stop Plano 0.022 9 Lens 4 −29.922 (ASP) 0.320 Plastic 1.639 23.5 −7.06 10 5.331 (ASP) 0.137 11 Lens 5 7.891 (ASP) 0.950 Plastic 1.544 56.0 9.27 12 −13.378 (ASP) D12 13 Lens 6 −7.765 (ASP) 0.470 Plastic 1.669 19.5 28.67 14 −5.661 (ASP) 0.200 15 Lens 7 −2.755 (ASP) 0.354 Plastic 1.587 28.3 −6.74 16 −9.509 (ASP) D16 17 Lens 8 15.278 (ASP) 0.800 Plastic 1.669 19.5 8.92 18 −9.589 (ASP) 0.320 19 Filter Plano 0.210 Glass 1.517 64.2 — 20 Plano 2.818 21 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). An effective radius of the stop 401 (Surface 1) is 2.200 mm.

As shown in Table 11 below, in each focusing state, three different zooming states between the short-focal-length end and the long-focal-length end of the image capturing lens system and corresponding optical data are also disclosed in this embodiment. The definitions of these parameters shown in Table 11 are the same as those stated in the 1st embodiment with corresponding values for the 4th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 10 and Table 12 as the following values and satisfy the following conditions:

TABLE 11 4th Embodiment Short-focal- Long-focal- length End length End First Focusing State f [mm] 8.50 11.05 12.75 14.45 17.00 Fno 3.24 3.75 4.05 4.33 4.69 HFOV [deg.] 13.7 10.4 9.0 7.9 6.8 D0 [mm] ∞ ∞ ∞ ∞ ∞ D5 [mm] 4.292 2.828 2.065 1.416 0.583 D12 [mm] 3.265 3.957 4.575 5.316 6.740 D16 [mm] 1.553 2.324 2.471 2.378 1.787 Second Focusing State Fno 3.25 3.76 4.06 4.34 4.69 HFOV [deg.] 13.7 10.4 9.0 7.9 6.8 D0 [mm] 800.000 800.000 800.000 800.000 800.000 D5 [mm] 4.292 2.828 2.065 1.416 0.583 D12 [mm] 3.347 4.079 4.733 5.524 7.056 D16 [mm] 1.471 2.203 2.312 2.171 1.471 (Vi/Ni)min 11.65 fG3/fG4 −0.96 V1 + V6 + V8 59.3 fL/fS 2.00 TDL/fL 0.92 fS/EPDS 3.24 |BLL/BLS − 1| 0.00E+00 fS/fG1 −0.83 |dTG34|/(TG3 + TG4) 0.13 fS/fG2 1.62 |TDL/TDS − 1| 0.00E+00 fS/fG3 −0.99 dTG12/dTG23 −1.07 fS/fG4 0.95 dTG12/TG2 −1.64 HFOVL [deg.] 6.8 TG1/TG2 1.07 HFOVS [deg.] 13.7 TG2/TG3 2.21 Y11L/lmgHL 1.06 TG3/TG4 1.28 Y11L/Y82L 1.00 f1/f3 1.38 Y11S/lmgHS 1.08 f4/f5 −0.76 Y11S/Y82S 1.04 fG1/fG2 −1.95 — —

In the 4th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment, so an explanation in this regard will not be provided again.

TABLE 12 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = 7.8725E−01 8.7599E+00 2.8663E+01 −6.7140E+00 −1.3027E+01 0.0000E+00 A4 = 3.2885E−03 1.7147E−02 −3.2989E−02   5.6106E−04  4.3692E−02 −9.2015E−03  A6 = −4.0734E−04  −1.0704E−02  4.7263E−04 −6.6138E−03 −2.4331E−02 1.6921E−02 A8 = 4.9553E−05 5.1108E−03 1.0262E−02  9.3225E−03  1.0378E−02 −4.2833E−03  A10 = 1.1379E−04 −7.9195E−04  −5.7494E−03  −5.5512E−03 −2.6001E−03 7.7378E−04 A12 = −3.3641E−05  −9.6334E−05  1.3352E−03  1.5662E−03  4.0337E−04 −4.3163E−04  A14 = 3.4122E−06 3.2229E−05 −1.1281E−04  −1.7186E−04 −4.5958E−05 6.6604E−05 Surface # 9 10 11 12 13 14 k = 0.0000E+00 0.0000E+00  0.0000E+00 0.0000E+00 1.4141E+01 0.0000E+00 A4 = 2.4982E−02 1.1710E−02 −1.7477E−02 4.9016E−03 1.6487E−02 1.0667E−02 A6 = 7.4874E−03 3.1586E−02  4.3656E−02 5.4514E−03 −9.8428E−03  −2.1758E−02  A8 = −3.3254E−03  −2.1853E−02  −1.9996E−02 −1.0043E−03  4.8389E−03 6.6673E−03 A10 = −4.4972E−04  6.1290E−03  5.2342E−03 6.4769E−04 −2.9323E−03  2.1829E−03 A12 = 1.4844E−04 −7.9767E−04  −7.2510E−04 −9.9915E−05  1.1323E−03 −1.6875E−03  A14 = — — — — −1.3316E−04  2.9059E−04 Surface # 15 16 17 18 k = 0.0000E+00 −5.7175E+00 −1.5404E+01 0.0000E+00 A4 = 2.3759E−02  1.6517E−02  1.0135E−02 1.1368E−02 A6 = −2.5781E−02  −8.1244E−03 −3.9061E−03 −3.5771E−03  A8 = 2.5322E−02  1.3335E−02  1.2967E−03 1.0598E−03 A10 = −7.8571E−03  −6.7096E−03 −3.4694E−04 −2.8558E−04  A12 = 3.7176E−04  1.3919E−03  5.0720E−05 4.1542E−05 A14 = 1.2492E−04 −1.0693E−04 −3.1506E−06 −2.5153E−06 

5th Embodiment

FIG. 17 is a schematic view of an image capturing unit at the short-focal-length end according to the 5th embodiment of the present disclosure. FIG. 18 is a schematic view of the image capturing unit at the long-focal-length end according to the 5th embodiment of the present disclosure. FIG. 19 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at the short-focal-length end according to the 5th embodiment. FIG. 20 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the image capturing unit at long-focal-length end according to the 5th embodiment. In FIG. 17 and FIG. 18 , the image capturing unit includes the image capturing lens system (its reference numeral is omitted) of the present disclosure and an image sensor 599. The image capturing lens system includes, in order from an object side to an image side along an optical path, a stop 501, a first lens element 510, a second lens element 520, a third lens element 530, a fourth lens element 540, an aperture stop 500, a fifth lens element 550, a sixth lens element 560, a seventh lens element 570, an eighth lens element 580, a filter 590 and an image surface 595. In addition, the image capturing lens system has a configuration of a first lens group G1 (including the first lens element 510 and the second lens element 520), a second lens group G2 (including the third lens element 530, the fourth lens element 540, the aperture stop 500 and the fifth lens element 550), a third lens group G3 (including the sixth lens element 560 and the seventh lens element 570) and a fourth lens group G4 (including the eighth lens element 580). The first lens group G1 has positive refractive power, the second lens group G2 has negative refractive power, the third lens group G3 has positive refractive power, and the fourth lens group G4 has negative refractive power. The image capturing lens system includes eight lens elements (510, 520, 530, 540, 550, 560, 570 and 580) with no additional lens element disposed between each of the adjacent eight lens elements.

The focal length of the image capturing lens system is varied by changing axial distances between the four lens groups (G1, G2, G3, G4) in a zooming process. As shown in FIG. 17 and FIG. 18 , the second lens group G2 is moved relative to the first lens group G1 along an optical axis in the zooming process, and the third lens group G3 is moved relative to the first lens group G1 along the optical axis in the zooming process. Furthermore, the image capturing lens system has a short-focal-length end as shown in FIG. 17 and a long-focal-length end as shown in FIG. 18 . In addition, when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, the second lens group G2 is moved along the optical axis toward the image side relative to the first lens group G1. It is noted that there is no relative motion between lens elements of each of the four lens groups in the zooming process.

The first lens element 510 with positive refractive power has an object-side surface 511 being convex in a paraxial region thereof and an image-side surface 512 being convex in a paraxial region thereof. The first lens element 510 is made of plastic material and has the object-side surface 511 and the image-side surface 512 being both aspheric.

The second lens element 520 with negative refractive power has an object-side surface 521 being concave in a paraxial region thereof and an image-side surface 522 being concave in a paraxial region thereof. The second lens element 520 is made of plastic material and has the object-side surface 521 and the image-side surface 522 being both aspheric.

The third lens element 530 with negative refractive power has an object-side surface 531 being concave in a paraxial region thereof and an image-side surface 532 being concave in a paraxial region thereof. The third lens element 530 is made of plastic material and has the object-side surface 531 and the image-side surface 532 being both aspheric. The third lens element 530 has at least one inflection point and at least one critical point in an off-axis region thereof.

The fourth lens element 540 with positive refractive power has an object-side surface 541 being convex in a paraxial region thereof and an image-side surface 542 being convex in a paraxial region thereof. The fourth lens element 540 is made of plastic material and has the object-side surface 541 and the image-side surface 542 being both aspheric. The fourth lens element 540 has at least one inflection point and at least one critical point in an off-axis region thereof.

The fifth lens element 550 with negative refractive power has an object-side surface 551 being concave in a paraxial region thereof and an image-side surface 552 being convex in a paraxial region thereof. The fifth lens element 550 is made of plastic material and has the object-side surface 551 and the image-side surface 552 being both aspheric. The fifth lens element 550 has at least one inflection point in an off-axis region thereof.

The sixth lens element 560 with negative refractive power has an object-side surface 561 being concave in a paraxial region thereof and an image-side surface 562 being concave in a paraxial region thereof. The sixth lens element 560 is made of plastic material and has the object-side surface 561 and the image-side surface 562 being both aspheric. The sixth lens element 560 has at least one inflection point in an off-axis region thereof.

The seventh lens element 570 with positive refractive power has an object-side surface 571 being convex in a paraxial region thereof and an image-side surface 572 being convex in a paraxial region thereof. The seventh lens element 570 is made of plastic material and has the object-side surface 571 and the image-side surface 572 being both aspheric. The seventh lens element 570 has at least one inflection point in an off-axis region thereof.

The eighth lens element 580 with negative refractive power has an object-side surface 581 being concave in a paraxial region thereof and an image-side surface 582 being convex in a paraxial region thereof. The eighth lens element 580 is made of plastic material and has the object-side surface 581 and the image-side surface 582 being both aspheric. The eighth lens element 580 has at least one inflection point and at least one critical point in an off-axis region thereof.

The filter 590 is made of glass material and located between the eighth lens element 580 and the image surface 595, and will not affect the focal length of the image capturing lens system. The image sensor 599 is disposed on or near the image surface 595.

In this embodiment, one of various focusing states of the image capturing lens system is provided, and the focusing state of the image capturing lens system is a state where the image capturing lens system focuses on an imaged object located at infinity.

The detailed optical data of the 5th embodiment are shown in Table 13 and Table 14, and the aspheric surface data are shown in Table 15 below.

TABLE 13 5th Embodiment Surface # Curvature Radius Thickness Material Index Abbe # Focal Length 0 Object Plano Infinity 1 Stop Plano −0.854  2 Lens 1 4.048 (ASP) 1.900 Plastic 1.545 56.1 5.02 3 −7.040 (ASP) 0.073 4 Lens 2 −15.563 (ASP) 0.306 Plastic 1.669 19.5 −13.35 5 21.131 (ASP) D5  6 Lens 3 −3.329 (ASP) 0.300 Plastic 1.544 56.0 −5.49 7 30.163 (ASP) 0.523 8 Lens 4 18.765 (ASP) 1.900 Plastic 1.669 19.5 6.38 9 −5.300 (ASP) −0.075  10 Ape. Stop Plano 0.127 11 Lens 5 −4.716 (ASP) 1.900 Plastic 1.669 19.5 −22.90 12 −7.913 (ASP) D12 13 Lens 6 −8.675 (ASP) 1.900 Plastic 1.669 19.5 −6.52 14 9.545 (ASP) 0.030 15 Lens 7 4.294 (ASP) 1.900 Plastic 1.544 56.0 3.51 16 −2.896 (ASP) D16 17 Lens 8 −1.311 (ASP) 0.318 Plastic 1.544 56.0 −4.87 18 −2.816 (ASP) 0.500 19 Filter Plano 0.210 Glass 1.517 64.2 — 20 Plano 1.995 21 Image Plano — Note: Reference wavelength is 587.6 nm (d-line). An effective radius of the stop 501 (Surface 1) is 2.455 mm.

The definitions of these parameters shown in Table 14 are the same as those stated in the 1st embodiment with corresponding values for the 5th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 13 and Table 15 as the following values and satisfy the following conditions:

TABLE 14 5th Embodiment Short-focal-length End Long-focal-length End f [mm] 10.04 14.97 Fno 3.46 3.54 HFOV [deg.] 13.8 9.6 D5 [mm] 0.121 1.443 D12 [mm] 1.011 1.189 D16 [mm] 1.625 0.105 (Vi/Ni)min 11.65 fG3/fG4 −1.06 V1 + V6 + V8 131.5 fL/fS 1.49 TDL/fL 0.92 fS/EPDS 3.46 |BLL/BLS − 1| 0.00E+00 fS/fG1 1.39 |dTG34|/(TG3 + TG4) 0.37 fS/fG2 −0.38 |TDL/TDS − 1| 1.44E−03 fS/fG3 1.94 dTG12/dTG23 7.43 fS/fG4 −2.06 dTG12/TG2 0.28 HFOVL [deg.] 9.6 TG1/TG2 0.49 HFOVS [deg.] 13.8 TG2/TG3 1.22 Y11L/ImgHL 0.98 TG3/TG4 12.04 Y11L/Y82L 1.18 f1/f3 −0.91 Y11S/ImgHS 0.98 f4/f5 −0.28 Y11S/Y82S 1.23 fG1/fG2 −0.27 — —

In the 5th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment, so an explanation in this regard will not be provided again.

TABLE 15 Aspheric Coefficients Surface # 2 3 4 5 6 7 k = −5.5813E−01  −3.8152E+01  2.8032E+01 −3.1906E+01 −1.7773E+01  0.0000E+00 A4 = 1.4138E−03  4.4387E−04 −7.8188E−03 −1.9761E−02  8.9512E−02  1.3439E−01 A6 = 5.4871E−05 −3.3864E−03 −3.7638E−03  3.5416E−03 −5.7438E−02 −7.0125E−02 A8 = 3.7883E−06  1.7198E−03  3.3709E−03  4.7579E−04  2.7337E−02  2.8873E−02 A10 = 4.9914E−07 −3.1794E−04 −8.4193E−04 −2.2854E−04 −8.7810E−03 −5.8497E−03 A12 = 9.4446E−08  2.1261E−05  9.0496E−05  2.2330E−05  1.5891E−03 −1.1792E−04 A14 = — — −3.3161E−06 — −1.2298E−04 — Surface # 8 9 11 12 13 14 k =  0.0000E+00  0.0000E+00 0.0000E+00 0.0000E+00  1.1946E+01  0.0000E+00 A4 = −2.5147E−02 −6.9305E−02 −3.6439E−02  2.4012E−02  1.9405E−02 −1.6812E−03 A6 =  8.0730E−03  8.5558E−02 7.8446E−02 −4.6833E−03  −4.8018E−03  1.4020E−03 A8 = −3.6854E−03 −5.5479E−02 −5.4832E−02  7.3599E−04 −3.2703E−04 −4.2961E−04 A10 =  2.0457E−03  1.3742E−02 1.2889E−02 −2.1978E−03   5.3012E−04  5.3686E−05 A12 = −8.3746E−04 −4.8456E−04 — 1.5367E−03 −8.8501E−05 −5.5102E−06 A14 = — — — −3.2380E−04  — — Surface # 15 16 17 18 k = 0.0000E+00 −2.2918E+00 −6.8251E−01 −1.0435E+00 A4 = −1.3325E−02  −5.2284E−03  2.6280E−01  2.0853E−01 A6 = 3.3180E−03 −4.9009E−04 −1.6909E−01 −1.2521E−01 A8 = −4.7268E−04   7.0878E−04  8.7891E−02  5.3682E−02 A10 = 2.5079E−05 −3.0003E−04 −3.1470E−02 −1.6218E−02 A12 = —  7.9436E−05  7.2828E−03  3.1851E−03 A14 = — −1.0909E−05 −9.6252E−04 −3.6064E−04 A16 = —  6.1686E−07  5.5283E−05  1.7730E−05

6th Embodiment

FIG. 21 is one perspective view of an electronic device according to the 6th embodiment of the present disclosure. FIG. 22 is another perspective view of the electronic device in FIG. 21 . FIG. 23 is a cross-sectional view of two image capturing units of the electronic device in FIG. 21 .

In this embodiment, an electronic device 20 is a smartphone including an image capturing unit 10, an image capturing unit 10 a, an image capturing unit 10 b, an image capturing unit 10 c, an image capturing unit 10 d, an image capturing unit 10 e, a flash module 21, a display unit 22, a focus assist module, an image signal processor and an image software processor.

In this embodiment, the image capturing unit 10 is a camera module including a lens unit, a driving device, an image sensor and an image stabilizer. The lens unit includes the image capturing lens system disclosed in the 1st embodiment, a barrel and a holder member. However, the lens unit may alternatively be provided with the image capturing lens system disclosed in other embodiments, and the present disclosure is not limited thereto. In addition, the image capturing unit 10 is a telephoto image capturing unit configured with a light-folding element LF6, and the light-folding element LF6 is disposed on the object side of the first lens element. Therefore, it is favorable for adjusting light travelling direction and folding optical axis, so that the total track length of the image capturing unit 10 and the thickness of the electronic device 20 are not restricted by each other. The imaging light converges in the lens unit of the image capturing unit 10 to generate an image with the driving device utilized for image zooming or focusing on the image sensor, and the generated image is then digitally transmitted to other electronic component for further processing.

The driving device can have zooming functionality or auto focusing functionality, and different driving configurations can be obtained through the usages of screws, voice coil motors (VCM) such as spring type or ball type, micro electro-mechanical systems (MEMS), piezoelectric systems, or shape memory alloy materials. The driving device is favorable for obtaining a better imaging position of the lens unit, so that a clear image of the imaged object can be captured by the lens unit with different object distances. The image sensor (for example, CCD or CMOS), which can feature high photosensitivity and low noise, is disposed on the image surface of the image capturing lens system to provide higher image quality.

The image stabilizer, such as an accelerometer, a gyro sensor and a Hall Effect sensor, is configured to work with the driving device to provide optical image stabilization (OIS). The driving device working with the image stabilizer is favorable for compensating for pan and tilt of the lens unit to reduce blurring associated with motion during exposure. In some cases, the compensation can be provided by electronic image stabilization (EIS) with image processing software, thereby improving image quality while in motion or low-light conditions.

The image capturing units 10, 10 a, 10 b are disposed on the same side of the electronic device 20, and the image capturing units 10 c, 10 d, 10 e and the display unit 22 are disposed on the opposite side of the electronic device 20. Each of the image capturing units 10 a, 10 b, 10 c, 10 d, 10 e can have a configuration similar to that of the image capturing unit 10, so the details in this regard will not be provided again. The image capturing unit 10 a includes an optical lens assembly and an image sensor (their reference numerals are omitted). As shown in FIG. 23 , the optical lens assembly of the image capturing unit 10 a has an optical axis OA6, and a movement direction D10 of lens groups of the image capturing unit 10 is perpendicular to the optical axis OA6; furthermore, the movement direction D10 of lens groups of the image capturing unit 10 is also perpendicular to an optical axis of the image capturing unit 10 b. Therefore, it is favorable for adjusting space arrangement so as to reduce the thickness of the electronic device.

The image capturing unit 10 is a telephoto image capturing unit configured with a light-folding element, the image capturing unit 10 a is a telephoto image capturing unit, and the image capturing unit 10 b is a wide angle image capturing unit. Half of a maximum field of view of the image capturing unit 10 a ranges from 15 degrees to 30 degrees, and half of a maximum field of view of the image capturing unit 10 b ranges from 30 degrees to 60 degrees. In other configurations, half of the maximum field of view of the image capturing unit 10 b can range from 35 degrees to 50 degrees. The image capturing units 10, 10 a, 10 b have different fields of view, such that the electronic device 20 can have a larger zoom ratio for more applications. The abovementioned electronic device 20 has the three image capturing units 10, 10 a, 10 b on the same side, but the present disclosure is not limited thereto. In other configurations, the electronic device may have at least two image capturing units disposed on the same side or have at least three image capturing units disposed on the same side.

The image capturing unit 10 c is a wide angle image capturing unit, the image capturing unit 10 d is an ultra-wide-angle image capturing unit, and the image capturing unit 10 e is a ToF (time of flight) image capturing unit, wherein the image capturing unit 10 e can determine depth information of the imaged object. The image capturing units 10 c, 10 d, 10 e and the display unit 22 are disposed on the same side of the electronic device 20, such that the image capturing units 10 c, 10 d, 10 e can be front-facing cameras of the electronic device 20 for taking selfies, but the present disclosure is not limited thereto.

The electronic device 20 includes multiple image capturing units 10, 10 a, 10 b, 10 c, 10 d, 10 e, but the present disclosure is not limited to the number and arrangement of image capturing units.

When a user captures images of an object, the light rays converge in the image capturing units 10, 10 a or 10 b to generate an image(s), and the flash module 21 is activated for light supplement. The focus assist module detects the object distance of the imaged object to achieve fast auto focusing. The image signal processor is configured to optimize the captured image to improve image quality. The light beam emitted from the focus assist module can be either conventional infrared or laser. In addition, the light rays may converge in the image capturing units 10 c, 10 d or 10 e to generate an image(s). The display unit 22 can be a touch screen, and the user is able to interact with the display unit 22 and the image software processor having multiple functions to capture images and complete image processing. Alternatively, the user may capture images via a physical button. The image processed by the image software processor can be displayed on the display unit 22.

7th Embodiment

FIG. 24 is a perspective view of an electronic device according to the 7th embodiment of the present disclosure.

In this embodiment, an electronic device 30 is a smartphone including an image capturing unit 10 f, an image capturing unit 10 g, an image capturing unit 10 h, an image capturing unit 10 i, an image capturing unit 10 j, an image capturing unit 10 k, an image capturing unit 10 m, an image capturing unit 10 n, an image capturing unit 10 p, a flash module 31, a focus assist module, an image signal processor, a display unit and an image software processor (not shown). The image capturing units 10 f, 10 g, 10 h, 10 i, 10 j, 10 k, 10 m, 10 n, 10 p are disposed on the same side of the electronic device 30, and the display unit is disposed on the opposite side of the electronic device 30. Each of the image capturing units 10 f, 10 g, 10 h, 10 i, 10 j, 10 k, 10 m, 10 n, 10 p can include the image capturing lens system of the present disclosure and can have a configuration similar to that of the image capturing unit 10, so the details in this regard will not be provided again.

The image capturing units 10 f, 10 g are telephoto image capturing units configured with light-folding element(s), the image capturing units 10 h, 10 i are telephoto image capturing units, the image capturing units 10 j, 10 k are wide angle image capturing units, the image capturing units 10 m, 10 n are ultra-wide-angle image capturing units, and the image capturing unit 10 p is a ToF image capturing unit. The image capturing units 10 f, 10 g with light-folding element(s) may respectively have a configuration, for example, similar to that as shown in FIG. 27 , FIG. 28 or FIG. 29 , and a description in this regard will not be provided again. In this embodiment, the image capturing units 10 f, 10 g, 10 h, 10 i, 10 j, 10 k, 10 m, 10 n, 10 p have different fields of view, such that the electronic device 30 has various magnification ratios so as to meet the requirement of optical zoom functionality. The electronic device 30 includes multiple image capturing units 10 f, 10 g, 10 h, 10 i, 10 j, 10 k, 10 m, 10 n, 10 p, but the present disclosure is not limited to the number and arrangement of image capturing units.

The smartphone in this embodiment is only exemplary for showing the image capturing unit of the present disclosure installed in an electronic device, and the present disclosure is not limited thereto. The image capturing unit can be optionally applied to optical systems with a movable focus. Furthermore, the image capturing lens system of the image capturing unit features good capability in aberration corrections and high image quality, and can be applied to 3D (three-dimensional) image capturing applications, in products such as digital cameras, mobile devices, digital tablets, smart televisions, network surveillance devices, dashboard cameras, vehicle backup cameras, multi-camera devices, image recognition systems, motion sensing input devices, wearable devices and other electronic imaging devices.

The foregoing description, for the purpose of explanation, has been described with reference to specific embodiments. It is to be noted that TABLES 1-15 show different data of the different embodiments; however, the data of the different embodiments are obtained from experiments. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. The embodiments depicted above and the appended drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. 

What is claimed is:
 1. An image capturing lens system comprising four lens groups, the four lens groups comprising eight lens elements, the four lens groups being, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group, the eight lens elements being, in order from the object side to the image side along the optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element, and each of the eight lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the first lens group comprises the first lens element and the second lens element, the second lens group comprises the third lens element, the fourth lens element and the fifth lens element, the third lens group comprises the sixth lens element and the seventh lens element, the fourth lens group comprises the eighth lens element, the first lens element has positive refractive power, the second lens element has negative refractive power, and at least one lens element in the second lens group, the third lens group and the fourth lens group has at least one inflection point in an off-axis region thereof; wherein a focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process, the second lens group is moved relative to the first lens group along an optical axis in the zooming process, the third lens group is moved relative to the first lens group along the optical axis in the zooming process, and the image capturing lens system has a long-focal-length end and a short-focal-length end; wherein an Abbe number of one of the eight lens elements is Vi, a refractive index of the one of the eight lens elements is Ni, a minimum value of Vi/Ni is (Vi/Ni) min, half of a maximum field of view of the image capturing lens system at the short-focal-length end is HFOVS, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, a maximum distance between an optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, a maximum distance between an optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the long-focal-length end is TDL, an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the short-focal-length end is TDS, and the following conditions are satisfied: 7.5<(Vi/Ni)min<12.3; 3.0 degrees<HFOVS<25.0 degrees; 0.50<Y11L/Y82L<2.0; 0.50<Y11S/Y82S<2.0; and |TDL/TDS−1|<1.0E−2.
 2. The image capturing lens system of claim 1, wherein the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, the maximum distance between the optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y82L, the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, the maximum distance between the optically effective area of the image-side surface of the eighth lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y82S, a focal length of the image capturing lens system at the long-focal-length end is fL, a focal length of the image capturing lens system at the short-focal-length end is fS, and the following conditions are satisfied: 0.65<Y11L/Y82L<1.5; 0.65<Y11S/Y82S<1.5; and 1.45<fL/fS.
 3. The image capturing lens system of claim 1, wherein the second lens group is moved along the optical axis toward the object side relative to the first lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end, a variation of axial distance between the first lens group and the second lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG12, an axial distance between a most object-side surface and a most image-side surface of the second lens group is TG2, and the following condition is satisfied: dTG12/TG2<−0.80.
 4. The image capturing lens system of claim 1, wherein a variation of axial distance between the third lens group and the fourth lens group when the image capturing lens system is zooming from the short-focal-length end to the long-focal-length end is dTG34, an axial distance between a most object-side surface and a most image-side surface of the third lens group is TG3, an axial distance between a most object-side surface and a most image-side surface of the fourth lens group is TG4, and the following condition is satisfied: |dTG34|/(TG3+TG4)<0.70.
 5. The image capturing lens system of claim 1, wherein an axial distance between a most object-side surface and a most image-side surface of the first lens group is TG1, an axial distance between a most object-side surface and a most image-side surface of the second lens group is TG2, and the following condition is satisfied: 0.80<TG1/TG2<1.4.
 6. The image capturing lens system of claim 1, wherein an axial distance between a most object-side surface and a most image-side surface of the second lens group is TG2, an axial distance between a most object-side surface and a most image-side surface of the third lens group is TG3, and the following condition is satisfied: 1.6<TG2/TG3<3.6.
 7. The image capturing lens system of claim 1, further comprising an aperture stop disposed in the second lens group, wherein the axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element when the image capturing lens system is at the long-focal-length end is TDL, a focal length of the image capturing lens system at the long-focal-length end is fL, the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the long-focal-length end is Y11L, the maximum distance between the optically effective area of the object-side surface of the first lens element and the optical axis when the image capturing lens system is at the short-focal-length end is Y11S, a maximum image height of the image capturing lens system at the long-focal-length end is ImgHL, a maximum image height of the image capturing lens system at the short-focal-length end is ImgHS, and the following conditions are satisfied: 0.50<TDL/fL<1.3; 0.65<Y11L/ImgHL<1.5; and 0.65<Y11S/ImgHS<1.5.
 8. The image capturing lens system of claim 1, wherein an Abbe number of the first lens element is V1, an Abbe number of the sixth lens element is V6, an Abbe number of the eighth lens element is V8, and the following condition is satisfied: 30.0<V1+V6+V8<105.0.
 9. The image capturing lens system of claim 1, wherein the image-side surface of the second lens element is concave in a paraxial region thereof, the object-side surface of the third lens element is convex in a paraxial region thereof, and the seventh lens element has negative refractive power.
 10. The image capturing lens system of claim 1, wherein the fourth lens element has negative refractive power, the fifth lens element has positive refractive power, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and the following condition is satisfied: −1.0<f4/f5<−0.10.
 11. The image capturing lens system of claim 1, further comprising a light-folding element, wherein at least one lens element in the first lens group, the second lens group, the third lens group and the fourth lens group is made of plastic material, and at least one lens element in the second lens group, the third lens group and the fourth lens group has at least one critical point in an off-axis region thereof.
 12. An image capturing unit, comprising: the image capturing lens system of claim 1; and an image sensor disposed on an image surface of the image capturing lens system. 